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AMD Radeon HD 7950 Review; Tahiti Pro Arrives

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SKYMTL

HardwareCanuck Review Editor
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Taking Image Quality to the Next Level

Taking Image Quality to the Next Level


In this section we take a number of games we have tested previously in this review and bring things to the next level by pushing the in-game settings to the highest possible level. All other methodologies remain the same.

Crysis 2
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Dirt 3

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Metro 2033

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Shogun 2: Total War

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The Witcher 2

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SKYMTL

HardwareCanuck Review Editor
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Temperature & Acoustics / Power Consumption

Temperature Analysis


For all temperature testing, the cards were placed on an open test bench with a single 120mm 1200RPM fan placed ~8” away from the heatsink. The ambient temperature was kept at a constant 22°C (+/- 0.5°C). If the ambient temperatures rose above 23°C at any time throughout the test, all benchmarking was stopped. For this test we use the 3DMark Batch Size test at its highest triangle count with 4xAA and 16xAF enabled and looped it for one hour to determine the peak load temperature as measured by GPU-Z.

For Idle tests, we let the system idle at the Windows 7 desktop for 15 minutes and recorded the peak temperature.


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We’ve broken up the results for this section into the two different cards tested: one being the reference design while the other is the HIS version that comes with a custom heatsink.

Let’s get things started with the reference design which uses the same heatsink as the HD 7970 but attains lower temperatures courtesy of lower heat production from the Tahiti Pro core. It actually attains some of the lowest temperatures we’ve seen from a reference card in some time.

Moving on to the HIS design, we were rightly impressed by its results as well. Even though it doesn’t use an extensive (and expensive!) vapor chamber, the core temperatures stayed below those of the reference design.


Acoustical Testing


Yes, we have finally added decibel testing to our repertoire and this section will expand in future reviews. What you see below are the baseline idle dB(A) results attained for a relatively quiet open-case system (specs are in the Methodology section) sans GPU along with the attained results for each individual card in idle and load scenarios. The meter we use has been calibrated and is placed at seated ear-level exactly 12” away from the GPU’s fan. For the load scenarios, a loop of Unigine Heave 2.5 is used in order to generate a constant load on the GPU(s) over the course of 20 minutes.

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This is one area where the HD 7950 excels since the lower amount of core heat allows the reference heatsink’s fan to spin at a lower speed than on other Southern Islands cards. The result is a noticeably quieter acoustical profile than our HD 7970 and we can almost guarantee you that it won’t be heard above in-game sounds or even the other fans in your case.


System Power Consumption


For this test we hooked up our power supply to a UPM power meter that will log the power consumption of the whole system twice every second. In order to stress the GPU as much as possible we once again use the Batch Render test in 3DMark06 and let it run for 30 minutes to determine the peak power consumption while letting the card sit at a stable Windows desktop for 30 minutes to determine the peak idle power consumption. We have also included several other tests as well.

Please note that after extensive testing, we have found that simply plugging in a power meter to a wall outlet or UPS will NOT give you accurate power consumption numbers due to slight changes in the input voltage. Thus we use a Tripp-Lite 1800W line conditioner between the 120V outlet and the power meter.

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To say we were impressed by these results would be a massive understatement. Due to the highly efficient 28nm manufacturing process HD 7950 was able to post simply incredible power consumption numbers. With a max board power (which should hardly ever be attained unless the core is heavily overclocked) of just 200W, it undercut the GTX 580 by a significant margin and even left the GTX 570 eating its dust. For reference, this is about how much a HD 6950 1GB consumes at load and yet this card easily hits GTX 580 performance levels. Now that’s progress folks!

The HIS card meanwhile demonstrates how different cores can have different levels of power consumption since its numbers are slightly above those of the reference card despite slightly cooler temperatures.
 

SKYMTL

HardwareCanuck Review Editor
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Overclocking Results

Overclocking Results


In order to overclock these cards, we used a vendor agnostic version of Sapphire's TRIXX software which allowed us to bypass the hard limits of 1100MHz on the core and 6.3GHz of memory speed. Unfortunately, neither the reference nor the HIS card were quite able to get up to those levels without voltage increases but we decided against overvolting in order to keep a level playing field. In addition, the fan speed profiles were left at their default values.

While we weren't quite able to get all the way up to 1.1GHz / 6.3Gbps, both of these cards were able to hit very respectable clock speeds. The performance increase was of course impressive, with framerates that were equal to or better than the HD 7970. Just remember that the results you see below are what we consider 24/7 stable and have been used for at least 6 hours of gaming to ensure stability.

Final Clock Speeds


Reference HD 7950:

Core: 1011MHz
Memory: 5948MHz (QDR)


HIS HD 7950:

Core: 998MHz
Memory: 5964MHz (QDR)


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SKYMTL

HardwareCanuck Review Editor
Staff member
Joined
Feb 26, 2007
Messages
12,841
Location
Montreal
Conclusion

Conclusion


When the HD 7970 was first reviewed we called it one of the best products released in the last two years and it’s now obvious that card wasn’t AMD's equivalent of a one hit wonder. The Southern Islands architecture continues to impress us in its Tahiti Pro form and depending on your needs, the HD 7950 may actually be significantly more appealing than its big brother.

While the Tahiti XT was obviously marketed towards anyone wanting the fastest graphics card on the planet without having to resort to dual GPU cards, the HD 7950’s goals are slightly less ambitious. It is meant to be a bridge between AMD’s flagship products and the upcoming, less expensive Pitcairn cores by offering performance that either meets or beats the GTX 580 without the high power consumption previous generation NVIDIA cards are known for. As we saw throughout this review, it achieves every one of these goals and then some.

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In terms of outright performance the HD 7950 trades blows with the aforementioned GTX 580 which shouldn’t come as any surprise given its entry price of $449. Speaking of price, this card is actually quite a good value when you consider NVIDIA’s flagship goes for at least $469 before mail in rebates are factored into the equation. So while the HD 7950 may not force NVIDIA’s hand on the performance front, at the very least it should drive down the GTX 580’s price.

Quite a few of you will understandably have a sense of “been there seen that” when looking at our benchmarks and that’s a feeling we share to a certain extent. Aside from its efficiency the HD 7950 really doesn’t necessarily bring anything new to the framerate table and performance does tend to drops more than a comparable NVIDIA card when anti aliasing is enabled. We do however expect this situation to improve as time goes on and AMD gets a better handle on writing drivers for their new architecture.

Raw performance is only one small part of the equation since this card’s lasting appeal lies in all of the small things it does right. Cool, quiet and efficient are three words not normally associated with enthusiast level GPUs but the HD 7950 hits all of these points. As the cost of energy rises, efficiency is becoming more and more important for gamers and enthusiasts alike so having a graphics card that can attain high performance without breaking the 200W barrier could prove to be invaluable in the long term.

Most people may want to know all about the HD 7970 but the HD 7950 will likely be the card they go out and buy. It is affordable, consumes very little power relative to the previous generation, performs at least as well as a GTX 580, has a fair amount of overclocking headroom and is ultimately much more affordable than a $550 flagship product. While it may not redefine its current price point, this is without a doubt the card to buy if you can’t justify spending more than $500 on an upgrade.



 
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