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ASUS M4A78T-E 790GX AM3 Motherboard Review

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FiXT

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ASUS M4A78T-E
790GX AM3 Motherboard Review



Manufacturer's Part Number: M4A78T-E
Price: $168CDN + Click Here to Compare Prices
Manufacturer's Product Page: ASUSTeK Computer Inc.
Warranty: 3 year limited warranty



An AMD-based motherboard review here at Hardware Canucks? Unbelievable! But definitely WAY past due. With the recent resurgence in the popularity of AMD processors, thanks to the surprisingly competent and extremely overclocking friendly Phenom II series, there is no better time to start off on this new path.

Speaking of new paths, in mid-February AMD launched the new Socket AM3 platform which finally brought forth official support for DDR3 memory. Along with this new socket, AMD launched three processors in the form of the Phenom II X3 710, X3 720 Black Edition, and the X4 810, with the promise of higher-end quad-core models to come (X4 925, X4 945, X4 955). Since the Phenom II's feature an integrated memory controller, the DDR3 support was added there so the actual AMD chipset didn't need any fundamental changes. Therefore, all motherboard manufacturers had to do to support these new CPU models was throw DDR3 memory slots on their current AM2+ motherboards, and voila! A brand new line-up of motherboards. None of them actually did this directly, but the transition certainly was not design intensive.

The motherboard that we are reviewing today is the ASUS M4A78T-E, which is based on the AMD 790GX/SB750 chipset combo. This enthusiast-oriented chipset has an Ace-in-the-Hole in the form of a very capable integrated graphics processor (IGP), the Radeon HD 3300. Along with this already strong selling point, the motherboard also features two mechanical PCI-E x16 2.0 slots, 2-way CrossFireX support, five SATA II ports, excellent RAID capabilities, eSATA and FireWire connectivity, six USB 2.0 ports, DVI, HDMI and D-Sub outputs, onboard 8-channel High-Definition audio, ExpressGate "instant-on" OS, Energy Processing Unit (EPU), and more.

The specs look great on paper, but it will take more than that to win our praise.

 
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MAC

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Specifications

Specifications




Manufactured on 55nm process, the small, low power 790GX northbridge was designed as an enthusiast-friendly chipset with the bonus of featuring an integrated graphics processor. The chipset features HyperTransport 3.0 support for all Phenom and Athlon X2 "Kuma" processors, and 22 PCI-E 2.0 lanes, 16 of them dedicated towards the graphics sub-system. In CrossFireX mode, those 16 lanes can be evenly split between two physical PCI-E x16 slots running at x8 each.

The IGP on the 790GX is known as both the RS780D and Radeon HD 3300. It is based on the RV610 core, and it features a 700Mhz core clock, 4 ROPs, 40 Shaders, and 128MB of DDR3-1333 SidePort memory built onto the motherboard, as well as a UMA option to access up to 512MB of system memory

In its current form, the 790GX is paired with the advanced SB750 southbridge, which supports six SATA II ports, AHCI, four RAID modes, up to twelve USB 2.0 ports, and one legacy parallel ATA channel among other goodies. This southbridge is also responsible for the popular Advanced Clock Control, which permits fancy tricks like allowing you to potentially enable the fourth core on Phenom II X3 720 BE processors and unlock the extra cache on the X4 810 models.

The main selling point of this brand new AM3 platform is the much awaited support for DDR3. Official support is for dual-channel DDR3-1333 in unganged mode, however the integrated memory controller (IMC) built into each processor does have a multiplier to support DDR3-1600. For those of you unfamiliar with the term unganged, the Phenom II's IMC is implemented as two seperate 64-bit controllers rather than a single 128-bit interface. As a result, the platform can either emulate a single 128-bit dual-channel mode (ganged) or operate as two independent 64-bit memory controllers capable of processing two memory requests simultaneously (unganged). The latter is faster in multi-threaded scenarios, while the former is better for single-threaded environments, but also puts more strain on the IMC and thus is relegated to slower DDR3-1066 memory speeds.

 
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MAC

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Features

Features





Thanks to architectural changes in the design of processors, such as the integrated memory controller, pure speed is no longer really a determining factor when it comes to selecting a motherboard. As such, manufacturer-specific features and overclocking capabilities are key elements when choosing between two similarly-priced AMD 790GX/SB750 motherboards. As mentioned previously, this is not necessarily a high-end motherboard, that distinction is appears reserved for models based on the 790FX chipset, but as you will see below it is certainly not lacking in the fancy gizmo department.

Let’s take a closer look at some of the included features:


 
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MAC

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Package & Accessories

Package & Accessories


Now that we have examined some of this motherboard’s abundant features, let’s take a quick peek at the package and accessories that ASUS have bundled with the M4A78T-E.


Click on image to enlarge

Here we have the shiny green box that has become ASUS's mainstay for AMD-based motherboards. It is widely regarded as a fairly attractive design, and we would tend to agree. The box is adorned with logos revealing this model's numerous features, and nowhere is this more true than on the back of the package, where you can find pretty much everything you need to know about the M4A78T-E.


Click on image to enlarge

The motherboard itself is packed in a regular anti-static (ESD) bag. This is standard and acceptable, but we would like to see a layer of foam material at the bottom of the box, just as an added layer of impact protection.

Next up, let's take a closer look at the accessories bundle, which as you will see is somewhat bare, but comes with all the essentials.


Click on image to enlarge

Here is a break down of the list of items which are included with this motherboard:

  • 1 x Floppy Cable
  • 1 x IDE Cable
  • 4 x SATA Cables
  • I/O Panel
  • ASUS front panel Q-Connector kit
  • Manual & Software CD

Nothing to get excited about, but we are happy to see that two of the SATA cables come with handy 90 degree connectors. We do wish that the SATA connectors had clips that ensure that they remain securely fastened to your hardware.
 
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MAC

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A Closer Look at the ASUS M4A78T-E

A Closer Look at the ASUS M4A78T-E




At first glance, the overall layout is top-notch. The ATX power connector, the floppy connector, and the IDE connector are all intelligently located at the edge of the motherboard, which is both convenient and functional. The SATA ports are located inwards, but since they are positioned near the bottom of the motherboard the potential for conflict with other components is reduced. We like the fact that there is a significant amount of room between both physical PCI-E x16 slots, which should allow the use of just about any aftermarket VGA cooling solution and even those insane triple-slot graphics cards from Palit. Overall, the designers have done an excellent job with this layout.


Now let’s take a closer look at the individual sections:


Click on image to enlarge

As you can see, the general CPU socket area on this motherboard is quite clean. If you remove the CPU cooler bracket (just need a phillips-head screwdriver), there really is a blank space to work with, which is ideal for those who utilize more extreme forms of cooling and who need to insulate around the socket area. Likewise, this should ensure compatibility with any size of air cooler or water block without issue.

This motherboard features an 8+1 phase VRM power design consisting of heatsink-cooled MOSFETs and high-quality sealed Yageo ferrite core chokes. For those of you wondering, the additional 1 phase is dedicated to the integrated memory/HT controller. Either way, this design officially supports 140W CPUs, and we have no doubt that it can handle even the most insanely overclocked Phenom II processor.

The cooling system on the M4A78T-E is fairly appealing but very simplistic, with no heatpipes or thick-based heatsinks. We will be testing the efficacy of this new cooling system in a later section.


Click on image to enlarge

Here we have the Halloween-themed orange & black dual-channel memory slots, which support a total of 16GB of system memory. ASUS has outfitted this model with a single-phase power design for the memory, which should ensure stable voltages to your quickly-depreciating DDR3 modules. At the edge of the motherboard, there is the perfectly located 24-pin ATX power connector and one of the three fan headers.


Click on image to enlarge

Here we get a good look at the tiny heatsink which is cooling the advanced SB750 southbridge. Starting from directly below the southbridge, there is the IDE connector, and then to the left the five vertical red SATA II ports, the non-colour-coded front panel header and the three USB headers. The SATA ports all support RAID 0/1/5/10 and JBOD. One thing worth mentioning is the socketed BIOS chip is identified with a green dot, which is extremely useful since no longer will you have to ship the entire motherboard if there is a fatal issue with the BIOS (bad flash, for example).

As mentioned above, the overall expansion slot layout and assortment is excellent. There are two full-sized PCI-E 2.0 x16 slots, two PCI-E x1 slots and two legacy PCI slots. As is the case on nearly every motherboard on the market, if you install dual-slot graphics cards in any of the PCI-E x16 slots, you automatically lose access to the slot directly under it. In this case it would be a PCI-E x1 and/or PCI slot. It should be noted that although this model supports CrossFireX, only the blue PCI-E x16 slot supports a full 16 electrical PCI-E lanes, while the black PCI-E x16 slot is limited to x8.


Click on image to enlarge

Starting from left to right, we have the Atheros L1E Gigabit LAN controller, which runs on the PCI-Express bus, and then the ITE IT8720F chip I/O controller which is responsible for hardware monitoring, fan speed management, and it supplies the legacy floppy support and PS/2 ports. Interestingly, ASUS has foregone Realtek in favour of a VIA VT1708S 8-channel High Definition Audio CODEC. This seems a like a cost-cutting measure to us, but we have no complaints about its audio quality or functionality. For those of you who have asked, we have included the ICS 9LPRS477CKL clock generator at the very top.

Next is a closer look at the uniquely designed northbridge cooler, and the revelation of the somewhat hidden single-phase power design for the 790GX northbridge. This chipset utilizes very little power and runs quite cool, so both of the aforementioned design elements are more than adequate. At the bottom of the image you may spot one of the three fan headers.


As expected, the rear I/O panel is quite crowded. From left to right, there is the single PS/2 keyboard port, two USB 2.0 ports, optical S/PDIF port, HDMI port, VGA & DVI ports, two USB 2.0 + FireWire + eSATA ports, Gigabit LAN port + two USB 2.0 ports, and finally the six audio jacks.


Click on image to enlarge

On the back on the motherboard we can spot the large metal backplate behind the CPU socket area. This is a new design feature that ensures that heavy cooling solutions will not bend and potentially damage the PCB or even the CPU socket itself. The other image is of one of the two plastic push-pins that secure the northbridge cooler. We would always prefer to see actual bolts being used, since it is simply a sturdier mounting method.
 
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MAC

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Hardware Installation

Hardware Installation


In the Hardware Installation section we examine how major components fit on the motherboard, and whether there are any serious issues that may affect installation and general functionality. Specifically, we are interested in determining whether the motherboard has adequate clearance levels in all critical areas.


Click on image to enlarge

Both the 24-pin ATX connector and 4-pin CPU power connector are ideally located, and there are zero issues accessing either of them.


Click on image to enlarge

On the AM2/AM3 platform, CPU coolers can only be installed in one orientation. In our case, the Thermalright Ultra-120 clears the low-profile MOSFETs cooler and it overhangs the first DIMM slot. This is actually slightly problematic because it makes installing and remove memory modules harder than it should be (particularly since we had to remove the 120MM fan every time), and it <b>may</b> prevent the installation of modules with particularly tall heatspreaders.


Click on image to enlarge

Clearly, there are no concerns about memory clips coming into contact with the back of the graphics card, and you can clearly see the sizeable gap between the CPU cooler and the northbridge cooler, which should ensure that even the largest heatsink will fit without issue.




Click on image to enlarge

When you install a dual-slot graphics card in the first PCI-E x16 slot there is a loss of access to one PCI-E x1 slot, but the other is still usable. It remains usable even when two dual-slot graphics cards are installed in the system, but obviously the the space is tight and only single-slot add-on cards will fit.

When a dual-slot graphics card is installed in the second PCI-E x16 slot there is a loss of access to one PCI slot, but the the other is still usable. Installing a dual-slot graphics card in the second PCI-E x16 slot doesn't create any compatibility issues, however...


Click on image to enlarge

...it does come awfully close to the five SATA ports. Thankfully, ASUS' engineers did a good job ensuring that none of the ports were lost in the name of multi-GPU goodness.


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There is nothing on the back of the motherboard that interferes with the Thermalright's backplate, and there is nothing on the back that should create compatibility issues with other models either.
 
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MAC

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Included Software

Included Software


Now that we have the motherboard unpacked and installed, it is time to take a look at some of the software utilities that ASUS has included with the M4A78T-E.


Here are the setup screens for the included software CD. As you can see, ASUS has really not left anything out when it comes drivers or utilities.


PC Probe II




Click on image to enlarge

PC Probe II is a system monitoring utility that displays information regarding fan speeds, component temperatures and voltages, as well as alerting users once preset thresholds have been surpassed. Although the M4A78T-E doesn't really have an abundance voltage readouts, PC Probe II is still a joy to use and it remains a superb piece of manufacturer-provided monitoring software.


AI Suite


The AI Suite provides basic system information, but its main function is to host shortcuts to five other ASUS utilities and features, namely the EPU-6 Engine, AI NAP, CPU Level Up, Fan Xpert, and TurboV. The AI NAP is an advanced sleep feature that allows users to put their computers to sleep without terminating any tasks. Fan Xpert allows users to select from 7 fan speed profiles that can be individually applied to any fan.


TurboV


Click on image to enlarge

TurboV is an overclocking utility that allows users to alter all essential system parameters, such as the CPU clock frequency, CPU voltage, memory voltage, CPU/NB voltage, VDDA voltage, HyperTransport (HT) voltage, northbridge (NB) and southbridge (SB) voltages, all without the need to reboot. Regrettably, unlike with the Rampage II Extreme, the settings that you apply in TurboV are not saved to the BIOS.


EPU-6 Engine


Click on image to enlarge

First showcased on the P5Q series, the EPU-6 Engine has been one of ASUS's most highly touted new features. This utility works in coordination with the EPU (Energy Processing Unit) controller in order to minimize your system's energy consumption. It does this by continuously monitoring and altering the speeds and voltages of the CPU, VGA card, hard drives and fans. There are four manually selectable modes and an automatic mode that varies settings according to system load. Regrettably, unlike Gigabyte's Dynamic Energy Saver (DES) technology, EPU-6 will not work when your system is overclocked, which obviously makes it a less attractive proposition from our power user point-of-view.


AMD OverDrive Utility


Click on image to enlarge & slowdown

When it works properly the AMD OverDrive Utility is very impressive piece of software. It provides in-depth system information, extensive monitoring capabilities, lots & lots of tweaking and overclocking functionality, benchmarking and stability testing capabilities, the works. However, as we mentioned, it is only great when it works properly, and that's the issue. All too often, the figures that AOD was displaying were flat-out wrong, which is obviously disconcerting when you are trying to tweak and overclock. We hope that it is simply some early teething problems between the utility and the new AM3 platform.


ExpressGate


Click on image to enlarge

Last, but certainly not least, is the ExpressGate “instant-on” operating system. This SplashTop Linux mini-OS allows for quick access to basic functions.


In mere seconds, users can web browse, view photos, chat via Pigdin, and even make internet calls through Skype. It was painless to set up thanks to its completely automated installation procedure, and a delight to use. As you can see in the image that is directly above, ExpressGate features an application dock somewhat similar to that which can found in recent Apple OS X versions. It is a convenient way to layout the four included applications. There are also a configuration panel with some very basic setup options.

Overall, ExpressGate is useful for those instances where your PC is off and you need the internet or Skype right away, but otherwise it becomes a novelty feature due to its inherent functionality limitations.
 
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MAC

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BIOS Rundown

BIOS Rundown


Everyone knows that the best designed, most feature-rich motherboard can easily be rendered mediocre by a subpar BIOS. Thankfully, as you will see below, ASUS has outfitted the M4A78T-E with an intuitive, tweaker-friendly BIOS. This is BIOS version 0801, which was recently supplanted by the newer version 1001.



Click on image to enlarge

To start off, we have the M4A78T-E welcome logo and the traditional AMI POST screen. Next up is the Main tab, it features the standard storage device list and even a basic System Information section. This System Information section lists some rudementary specification info, including the BIOS date & version, the type of processor and the amount of memory installed.


Ai Tweaker




Click on image to enlarge

As on all non-Republic of Gamers models, the Ai Tweaker is where all the fun happens. It is in this tab that you can find all the vital tweaking options pertaining to the CPU multiplier, CPU base frequency, DRAM frequency, CPU/NB frequency, HT Link speeds, etc. As you can see, aside from the CPU base frequency, which is entered manually, all the important system frequencies have user-friendly drop-down menus. All the voltages options are manually entered, which we actually prefer since it is generally quite a bit faster.


Memory & CPU Sub-Menus



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Within Ai Tweaker, there are two sub-menus which reveal a mightily impressive number of memory options. We aren't sure if all AM3 motherboards are like this one, but we were certainly pleasantly surprised to this such in-depth options on a mainstream model.


Advanced Tab



Click on image to enlarge

In the Advanced tab, you can enable and disable various AMD-specific technologies like Cool'n'Quiet and also access the very popular Advanced Clock Calibration option. This is the setting that allows you to potentially enable the fourth core on Phenom II X3 720 BE processors and unlock the extra cache on the X4 810 models. There is no guarantee that it will work on your own processor, but when it does, it is apparently sweet feeling (...we were not so fortunate with our own 720). This tab also gives you access to the various chipset features, such enabling/disabling the IGP and tweaking its numerous settings. You can even overclock the IGP, if you are so inclined.


Power Tab



Click on image to enlarge

The Power tab allows you set how your computer can resume from various suspend/standby modes, and it gives you access to the Hardware Monitor. As usual we wouldn't mind a few more temperature and voltage readouts, but sadly what <b>is</b> provided is actually above-average. The venerable Q-Fan fan control functions are also found within the Hardware Monitor.


Boot Tab


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The Boot tab is essentially where you set storage device priority and select the boot drive, you can also set supervisor and user passwords, and disable the M4A78T-E welcome screen.


Tools Tab


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The last section contains EZ-Flash 2, which is a built-in utility that greatly simplies the BIOS updating process. You can easily update your BIOS from a ROM file located on your hard drive(s), USB flash drive(s), or even a CD. It's quick, painless, and it takes the worry out of BIOS flashing.

The ASUS O.C Profile feature gives users the option to save and switch between BIOS profiles, for example an everyday profile and a benchmarking profile. Not only is this infinitely quicker than manually inserting every setting, but the profiles can be saved and shared among other Rampage II Extreme owners. We are glad to see that ASUS have listened to our recommendations, and increased the number of profiles from a meager 2 to a more reasonable 8 profiles.

Lastly, in this section, you can configure or disable the ExpressGate instant-on OS and utilize the AI NET 2 to diagnose your network before booting into the OS.


Overall, this is a functional, intuitive BIOS with an abundance of options, and it is excellent for a mainstream motherboard. We wish there was further monitoring functionality, but that is really the only minor shortcoming.
 
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MAC

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Test Setup & Methodologies

Test Setup & Methodologies




Test Platform:

Testing will occur on a Highspeed PC Standard Top Deck Tech Station and not in a traditional case. This allows easier access to the motherboard for the constant poking and prodding that is required during the reviewing process. The setup remained as pictured during the duration of the benchmarking and stability overclocking process.



Phenom II vs. Core 2 Duo Size Comparison - Click on image to enlarge



Overclocking Methodology



Although this is not a high-end model, that is thus far reserved for 790FX-based motherboards, we are excited to test out the much-hyped overclocking capabilities of this new AM3 platform. We expect to achieve some impressive overclocking results and we are definitely going to find out what it is truly capable of. The overclocking section is definitely the part of our reviews that we take the most pride in, and we spend an excruciating numbers of hours testing, tweaking, failing, and succeeding in order to give you the best possible insight into each motherboard’s overclocking capabilities. After all, if you are anything like us, the overclocking section is the first (and often last!) part that you read when checking out a motherboard review.

For the purposes of this review, our overclocking efforts will primarily focus on three main areas: highest stable CPU bus overclock, highest stable CPU bus overclock while using the IGP, highest stable memory overclock, and highest stable CPU overclock.

In these four overclocking tests we put an emphasis on stability. While the question “What is stable?” could be debated endlessly, we have devised a methodology that combines a wide range of programs that test the stability of the entire system.

Here is the suite of applications that will be run in order to validate each of the overclocks:

  • Eight 32MB instances of SuperPi Mod 1.5 (ran at the same time)
  • 3+ hours of dual Prime 95 v25.6 using the Stress Testing Blend
  • 1 hour of OCCT Auto 1H Medium Data Set OCCT v3.0.1
  • 3+ hours of dual HCI MemTest in Windows using all available memory
  • Multiple loops of 3DMark 06 (30 minutes of looping the full tests each)
  • 1 hour of game play in Left 4 Dead & Crysis @ 1680x1050

Altogether, the above suite should provide enough stress testing to ensure a completely stable overclock, however we are always up for new suggestions. As always, no two systems are ever alike, so your results may vary. Also, overclock at your own risk! The Phenom II AM3 platform is brand new, and although we are somewhat conservative with our voltage estimates, there is always the possibility that you could damage any and all of your components. If you aren’t fully confident in what you are doing, feel free to stop by our forums and our helpful community will be glad to offer some assistance.


Benchmark Methodology



For this review, our benchmarking section will focus solely on the ASUS M4A78T-E, in stock and overclocked configuration. The reasoning behind this approach is that there is a minuscule clock-for-clock performance difference between two motherboards that share an identical chipset and declaring one product a winner based on a 1% performance advantages seems futile to us.


We have outlined the two setups in the sample graph above. The glowing orange results will indicate the performance at the BIOS defaults. The only changes that will be made are to the CPU multiplier in order to get it running at the desired frequency. Every other setting will be at the default that the BIOS sets. The red results are achieved using the highest stable CPU overclock for this particular setup.

For all of the benchmarks, appropriate lengths are taken to ensure an equal comparison through methodical setup, installation, and testing. The following outlines our testing methodology:

A) Windows is installed using a full format.

B) Intel Chipset drivers and accessory hardware drivers (audio, network, GPU) are installed followed by a defragment and a reboot.

C) Programs and games are then installed followed by another defragment.

D) Windows updates are then completed installing all available updates followed by a defragment.

E) Benchmarks are each ran three times after a clean reboot for every iteration of the benchmark unless otherwise stated, the results are then averaged.

We have listed the benchmark versions on each graph as results can vary between updates. That should about cover everything so let's see what kind of numbers this motherboard puts up in the overclocking section and in our chosen suite of benchmarks.
 
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MAC

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Overclocking Results

Overclocking Results



First and foremost, if you are completely new to Phenom II overclocking we highly recommend that you check out our article on the subject, aptly titled "Hardware Canucks: Benchmarkers Guide to the Phenom II". Although it is limited to the AM2+ versions, the fundamentals remain the same as with the new Phenom II AM3 processors.

In our tests, we will be using a Phenom II X3 720 Black Edition processor, codename 'Heka', which is obviously a triple-core model. It features a 2.8Ghz clock speed, 1.5MB of L2 cache, 6MB of L3 cache, and most important for our purposes, fully unlocked CPU multipliers. As a result, we will be able to determine what kind CPU bus speeds this motherboard is capable of, with both the IGP enabled and disabled. We'll also be seeing how well our processor scales on this model, although we don't really a point of reference to compare it to yet as this is our first AM3 motherboard. Lastly, and the whole point of the AM3 platform, is the DDR3 memory, and we'll see what kind of memory speeds we can achieve using two modules from our recently reviewed OCZ 6GB PC3-12800 Platinum memory kit. Across four results, we have disabled Cool'n'Quiet and C1E in the BIOS, and we kept the CPU/NB frequency and HT Link speed as close as possible to their default 2000Mhz mark.

So without further ado, let's move onto the results:


Highest Stable CPU Bus Overclock


Much like the Intel Core i7's base clock (bclock) frequency, Phenom II's have a CPU bus frequency that is generated and thus limited by the motherboard. Although this frequency is more or less relevant on an unlocked CPU multiplier chip like the one we are using, those who purchase the X3 710 and X4 810 will need to increase this bus frequency in order to overclock their processors. As you can see above, our unit proved to be a very capable overclocker. From the stock 200Mhz, we were able to achieve a heady 285Mhz. To put that into perspective, this would permit you to overclock the 710 or 810 (both have a 13X multiplier) up to a solid 3700Mhz. This result was dead simple to achieve as well. No special tricks or tweaks, we just left all the voltage options on AUTO, manually selected an appropriate memory frequency, and started increasing bus frequency until we found the high mark. The epitome of simplicity.

Having said that, we did notice an "FSB Hole" in the 240Mhz range, in which the system was inexplicably unstable. Contrary to common logic, the solution was simply to overclock the system higher and stability was no longer an issue once we reached the 250 mark. From what we've been reading on various message boards this "FSB Hole", if present at all, can appear anywhere in the CPU bus frequency range so it can be somewhat troubling to diagnose properly. Therefore, keep this in mind if you do own and overclock with this motherboard. This issue is present with BIOS version 0801, and it is quite possible that ASUS will rectify this issue in a future BIOS update.


Highest Stable CPU Bus Overclock - IGP Enabled


Since Radeon HD 3300 integrated graphics processor is an integral part of the 790GX northbridge, we were very interested in determining whether having it enabled would have any impact on the overclocking of the bus frequency. As you can see, it did have an impact, but a relatively small one. In our eyes, a 10Mhz loss is quite acceptable in exchange for the free functionality of the IGP. It is good to see that those who are more interested in pure CPU power than fancy graphics will not be held back when overclocking with the IGP in use.


Highest Stable CPU Overclock


By now most of you are aware of the Phenom II's vastly superior overclocking capabilities when compared to the original Phenom processors, and clearly the switch to DDR3 has not had a negative impact. While our CPU overclock is not as remarkable as all the 4Ghz results we are seeing everywhere, it remains a solid 32% overclock. As we mentioned previously, we have no point of reference with this processor. Therefore, we cannot be 100% sure that it would not achieve a superior result on another motherboard, however we have no reason to suspect that the M4A78T-E was holding back our progress in any way, shape, or form.


Highest Stable Memory Overclock


Finally...DDR3 on an AMD platform, terrific right? Regrettably, at least at this point in time, it does not appear that the new AM3 integrated memory controller has much headroom when it comes to memory overclocking. We tried everything; every voltage option, timings, skews, drive strengths, tweaks, and tricks but to no avail. No matter what 4GB DDR3 memory kit we used, there simply no way ensure stability above 1660Mhz. Other Phenom II AM3's might be slightly better, but there is a reason why memory manufacturers haven't really jumped on the AM3 bandwagon. To ease the strain on the IMC, we whipped out of our best DDR3-2000+ capable 2GB kit, and although we were able to achieve up to 1760Mhz with stability, anything higher would fail our stress tests. In order to achieve these results, we used up to 1.4215V for the CPU/NB, any higher did not increase stable memory overclocking headroom. As important as the CPU/NB was the NB voltage, which we had to increase to 1.40V in order to reliably load Windows.

Although we kept the CPU/NB (ie: integrated memory controller) frequency as close to the stock 2000Mhz as possible during our tests, this is the frequency that you want to increase in order to achieve the best possible bandwidth numbers. In doing so however, we encountered a slight BIOS issue. Anytime we selected a CPU/NB frequency above 2900Mhz it would simply revert back to the stock 2000Mhz. We're hoping this gets fixed in a future BIOS update since our processor definitely seemed to have some additional headroom.
 
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