Intel Lynnfield Core i5-750 & Core i7-870 Processor Review

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Overclocking Results

Overclocking Results

Overclocking the Lynnfield/P55 platform is quite similar to the Bloomfield/X58 platform, but easier since there is no need to worry about the X58 northbridge or QPI Link. More importantly though, since the Uncore has now been isolated from the DDR3 memory frequency, Lynnfield can potentially achieve much higher memory speeds since it is no longer artifically limited by the Uncore ratio. With regard to voltage limits, we really haven't heard anything official, but if you are using air cooling, we recommend that you stay below these values for 24/7 operation: vCore up to 1.40V (cooling permitting), VTT up to 1.35V, and vDimm up to 1.70V. Given reviewing time constraints we haven't stress tested the following overclocks as thoroughly as we usually do, but as you will see we did utilize a healthy assortment of benchmarking and stress testing utilities. Turbo Boost was disabled for these tests, since the constantly changing CPU multiplier would make overclocking significantly more difficult.

Given it's budget-friendly $199 price tag, the Core i5-750 will be the main focus of our overclocking efforts, since we don't honestly expect the i7-870 to appeal to many overclockers given its bloated price tag.

Highest Stable CPU Overclock: i5-750


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For starters, forgive the missing 'Core Voltage' readout, for some reason it would sometimes disappear on us when we overclocked. Nevertheless, to achieve 4.0Ghz we needed 1.3875V with V-droop disabled. We increased the Uncore/QPI voltage to 1.15V out of precaution, and disabled Turbo, but otherwise this overclock was as simple as raising the base clock (BCLK) to 200Mhz.

Highest Stable BLCK Overclock: i5-750


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We were able to achieve a 210Mhz BLCK, but at this point in time, we aren't entirely sure whether the motherboard or the CPU was the limiting factor. We can load Vista at up to 220Mhz, but any attempt at stress testing would result in a system lock no matter the amount of vCore or Uncore/QPI voltage used.

Highest Stable Memory Overclock: i5-750


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We were certainly not disappointed on the memory overclocking front, having achieved an excellent DDR3-2100 9-9-9 result. This was achieved with 1.30V Uncore/QPI Voltage and 1.70 Vdimm. We could have tightened the timings, but the Kingsberg board would not recognize the 8-9-8 timing settings, instead defaulting to 9-9-9. This is a shame since our Patriot Sector 5 Viper II 4GB DDR3-2000 8-8-8-20 memory kit was barely breaking a sweat thanks to its top-notch Elpida Hyper BASE ICs.

Highest Stable CPU Overclock: i7-870


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With Hyper-Threading enabled, the 870 runs pretty hot. As a result, we couldn't safely use as much voltage as with the i5-750 or the temperatures would start hitting 90C mark. Nevertheless, our sample was good for a solid 4.0Ghz at 1.35V with v-droop disabled. We needed 1.28V Uncore/QPI to stabilize this overclock.

Highest Stable BLCK Overclock: i7-870


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This i7-870 was nowhere as BCLK friendly as the i5-750, topping out a mere 202Mhz with 1.35V Uncore/QPI voltage. This might seem disappointing, but given the 22X stock multiplier that would be enough for up 4.44Ghz.

Highest Stable Memory Overclock: i7-870


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Using the same 1.35V Uncore/QPI and 1.70Vdimm settings as with the i5-750, we were able to achieve a 30Mhz higher memory frequency with our i7-870 chip. I think that most people will agree that DDR3-2138 is not too shabby at all, especially since it represents a 60% increase over the reference DDR3-1333 specification. Keep in mind that there is likely a whole lot more memory frequency headroom with this setup, but we are just being conservative with the Uncore/QPI voltage until we become more familiar with the platform.

 

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Conclusion

Conclusion

If you have read this article from beginning to end, our opinion of the Lynnfield processors should be quite evident: two enthusiastic thumbs up! Having said that, we were really dealing with two distinctly different offerings today. On one hand we have the i5-750 that performed extremely well in nearly every single test while not costing an arm and a leg. On the other hand, we have the 750's alter ego; the high-flying i7-870. Both are at their own ends of the Lynnfield spectrum and as such really gave us an interesting take on how things are going to look in Intel's new lineup.

The i7-870 is a 'mainstream offering' by name only given its $562 price tag, which is on the outside looking in to the mainstream segment. Yes, it performs extremely well, matching the $999 Core i7-975 Extreme Edition on several occasions, but we simply can't get over the price. Thankfully, the i7-860 is almost $300 cheaper, and only 133Mhz slower, which makes it the no-brainer choice between the two. It is a multi-threading monster in a mainstream arena with no viable competition in sight.

Realistically, not everyone needs or even has the budget for a $284 processor, and that is where the the decidedly more budget-friendly $199 i5-750 comes into play. Despite having one hand tied behind its back due to a lack of Hyper-Threading, this model put the proverbial smackdown on the Core i7-920, pretty much across the board. It also resoundingly outperformed two close competitors in the form of the Phenom II X4 945 and the Core 2 Quad Q9550. Besides which, as we all know, even in the enthusiast realm truly multi-threaded applications are few and far between even years after the first dual-core processor was released. We see this again and again with a multitude of games that just can't seem to properly take advantage of multiple threads. Sure, it's nice to have the potential for 8 threads in some applications, but to us the 750 is the current darling of the Lynnfield lineup for those of you who want a great performing, power efficient processor with solid overclocking headroom.

Power consumption is something that just has to be mentioned in this conclusion. In a world where "Think Green" has become the new gateway drug for countless make-believe power consumption "technologies" that end up being nothing but snake oil, it is good to see Intel delivering on a promise of increasing efficiency with every generation. The simplification of the P55 chipset as well as countless other advances have contributed to make the Lynnfield chips some of the most efficient around and have set a new benchmark in the performance per watt category.

Intel have successfully brought the Nehalem microarchitecture to the mainstream, and in spectacular fashion. Never before have Intel released a mainstream processor line that overlapped so much with their high-end offerings performance-wise.

So where does this leave Core i7 900 series owners and their X58 motherboards? Well first and foremost, those who built a Bloomfield/X58 setup can rest assured that their system has many years left in the tank. Secondly, they will have exclusive access to Intel's upcoming Core i7 900 series 'Gulftown' 32nm six-core processors, and maybe even some faster quad-core 32nm Core i7 models as well. There is a guaranteed upgrade path for LGA1366, but it likely won't be cheap. On the other hand, the new LGA1156 platform appears to be a bit of a dead end in some ways as the i7-870 will probably be the highest-end LGA1156 processor available for the foreseeable future. Down the road, if you performance levels greater than the i7-870 can provide, you will have to buy a whole new platform.

All in all though, there can be no doubt that Lynnfield will be a great success since it improves upon the last mainstream generation in every conceivable way. It provides substantially better performance when it's needed most, it is impressively energy-efficient, and fairly affordable too when you consider that P55 motherboard's will retail for as low as $100. What's not to love?

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