ASUS P7P55D Deluxe Lynnfield Motherboard Review

Manual Overclocking Results

If you are buying or building a Lynnfield/P55 system chances are that you don't already own a Core i7/X58 system. Many of you will likely be transitioning over from Intel Core 2-based systems,and you have to realize that overclocking Core i5/i7 processors is quite different than with the previous Core 2 architecture. There are now four important clock speeds (CPU/BCLK/MEM/QPI) and three multipliers (CPU/MEM/QPI) to tweak, as well as five different voltages. Put simply, there are lot of new variables and potential limitations that an overclocker must now take into consideration. At the moment, no one is an expert when it comes to Lynnfield overclocking, and we are all learning new tricks and tweaks on a weekly basis. At this point in time, for our overclocking tests we have a imposed a few relatively conservative voltage limits, namely vCore up to 1.40 vCore, VTT/IMC up to 1.35V, and vDIMM up to 1.70V. It is our estimation that these voltages can be safely used 24/7 without seriously shortening the lifespan of any components...with proper cooling of course.

Highest Stable BCLK Overclock

BCLK overclocking has thus far proven to be a very interesting experience for us. On the one hand, our i5-750 sample has proven quite BCLK friendly, achieving a stable 212Mhz with as little as 1.21V VTT/IMC. However, no matter how much additional voltage we give the chip, it wouldn't gain 1Mhz of additional stable BCLK headroom. On the other hand, our i7-870 is a voltage hog, needing a full 1.35V VTT/IMC in order to stabilize a 202Mhz BCLK. Why this huge disparity between chips? Well, to be honest, our particular i7-870 sample is probably just a little weak in the BCLK area. We have seen several i7-800 series retail chips that are stable in 210-215Mhz BCLK range.

With regard to the P7P55D Deluxe, we were able to squeeze an additional 2Mhz BLCK from our i5-750 sample compared with the Intel DP55KG, but no additional headroom from the i7-870 which was only stable up to 202Mhz on either motherboard.

Highest Stable CPU Overclock

In our search for the highest stable core clock, we were able to break 4.0Ghz mark on both chips. Specifically, we were able to achieve 4088Mhz with 1.40 vCore on the i5-750, and 4044Mhz at 1.35 vCore on the i7-870. Why did we only use 1.35V on the 870? Heat! HyperThreading increases core temps by a solid 10C, so at these settings we were already well within the mid-80C mark, with the very occassional peak into the low 90C's. Once Thermalright releases a proper LGA1156 mounting mechanism, instead of the push-pin design that was bundled with our MUX-120, we should be able to push both chips even higher and with lower temps too thanks to better contact and mounting pressure.

Both of these results are slightly better than what we achieved on the DP55KG, but admittedly we were time-constrained when achieving those overclocking results.

Highest Stable Memory Overclock

While searching for the highest stable memory overclock, we pushed aside our weaker i5-750 and focused on the i7-870. In doing so, we were able to achieve an impressive DDR3-2200/PC3-17600 9-9-9-24-1T @ 1.65V. Let's be clear that this memory frequency, while impressive, was absolutely limited by our self-imposed 1.35V VTT/IMC voltage limit. The i7-870 integrated memory controller was the bottleneck in this case, not the motherboard, nor our Patriot Sector 5 Viper II DDR3-2000 8-8-8 memory modules, which feature awesome Elpida Hyper ICs.

The P7P55D Deluxe is rated up to DDR3-2200, which is exactly what we achieved, and which is a full 62Mhz (DDR) higher than our result with the DP55KG. Not too shabby at all.

Overall Stable System Overclock

The Overall Stable System overclock is not only the configuration that we would personally use 24/7, but it is also the configuration that we used in the benchmarks section. We are running our Core i7-870 at 4.0Ghz with a 200Mhz BCLK. With the P7P55D Deluxe we could have used the unlocked CPU 24X and a lower 167Mhz BLCK to achieve the same CPU core clock, but we chose the lower multiplier/higher BCLK approach since it allowed us to have a very high Uncore frequency. Our 3600Mhz Uncore is a full 50% faster than the stock 2400Mhz, and the performance benefits are substantial, much greater than what could be achieved by simply overclocking the memory. Although we could have elected to run the memory at DDR3-2000, we chose a low latency/low voltage approach by running the memory at DDR3-1600 7-8-7 at 1.55 vDIMM. This should be achievable with just about any mainstream kit, no need to speed on fortune on an enthusiast kit.


Now these are the results that we were able to achieve manually using this motherboard, but the P7P55D Deluxe is outfitted with two seperate auto-overclocking technologies that ASUS have been touting for months, one BIOS-based and one software-based. Just how good (or bad) are they? Let's find out...