Overclocking

If you are on a strict budget but still want a P55 motherboard with a full feature set that offers solid overclocking abilities, the ASRock P55M Pro is a very good choice.

Core i5/750 8GB Results


Our maximum stable overclock on air-cooling with the Core i5/750 resulted in a 4.1GHz clock speed at a respectable 216MHz Bclk with a variety of 8GB DDR3-2000+ kits. The primary voltages settings were 1.3625V VCore, 1.36V VTT, 1.80V PLL, and 1.64V VDimm. The VCore setting is deceiving. We had to run the board with Load Line Calibration (Vdrop off) enabled for stability. This was with setting the voltage manually to 1.3625V or with the Overdrive Offset enabled with +0.1625V.

This meant the VCore would rise to 1.384V~1.392V during load conditions. It was either this or run the processor at 1.425Vand accept Vdroop of 0.05V. Also, we had to relax memory timings to DDR3-1728 at 8-8-8-20 1T settings. VDimm would have to be increased to 1.71V (the next step from 1.64V) in order to run C7 settings on this board.




We could improve memory timings or speed with the Bclk set to 215 and dropping our CPU multiplier to 19, but that required a VCore increase to 1.375V as we left VTT at 1.36V along with enabling Vdrop in the BIOS. Memory had to be increased to 1.71V for C7 operation and PLL remained at 1.80V. We could run the memory at DDR3-2152 at 9-9-9-27 2T but VTT had to be increased to the next step at 1.42V and PLL to 1.94V. Performance was not measurably different from our 19x206 setting in application testing, but CPU temperatures were up 3C. Even though these settings passed our stability test suite, we just felt like the trade off in increased voltages was not worth some very minor memory performance gains.

Core i7/860 8GB Results


Our i7/860 fared better clocking wise than the i5/750, but we could not match the 21x205 speeds generated with the Gigabyte board without raising VCore to 1.425V. We ended up at a perfectly stable 20x205 setting resulting in a 4.1GHz clock speed with 8GB at DDR3-1740 at 7-7-7-24 1T timings. However, our voltage settings were lower due to the decreased clock/memory speeds.

VTT is set to 1.36V, PLL at 1.94V, VDimm at 1.64V, and VCore at 1.350V with the Overdrive Offset/VDrop enabled. Under load conditions VCore was +.015V~+.02V with Vdrop enabled and -.055V~-.06V with it disabled. Our Core i7/870 clocks matched these exactly.

Core i7/860 4GB DDR3-2400 Results


ASRock advertised DDR3-2400 speeds so we decided to verify their claim. Unfortunately, the board had serious problem running our OCZ DDR3-2400 Blade kit at 2400 with the stock 9-10-9-24 1T settings on 1.71V. We just could not dial in stability at that memory speed. We had to settle for DDR3-2000 7-8-7-24 1T timings at 1.64V. Of course, those memory speeds is more than fast enough for application usage and let’s face it, nobody will be buying this board thinking they are going to break world records.



Thoughts

The overclocking results are solid and certainly 4.1GHz speeds are fast enough for most. Let’s face it; if you have to have the best possible OC performance, then the Gigabyte UD2 board is simply better. We have no concerns recommending the ASRock board for 24/7 overclocking use. When it is overclocked, the board is very stable. As a bonus, it had no problems doing an S3 resume with the Bclk set to 215.

In regards to voltage regulation, ASRock follows Intel’s guidelines exactly. This has advantages as the processor is always running at specifications when it comes to Vdrop and Vdroop, but the disadvantage is that one has to really take time to tune the board to get the most out of it. The board was really designed to get you to about 90% of your component’s capabilities and that is it. Trying to tune another 5% performance improvement was possible, but very time consuming and frustrating to be honest.

In most cases I would not use the word frustrating, but compared to the Gigabyte UD2 board, that next five percent in tuning consumed about five times as much time on the ASRock board and we still did not match the speeds on the Gigabyte board. Granted, we are talking about numbers that look really good in screenshots and yes, application performance like encoding and file compression will show a small improvement. However, one has to ask if it is worth it.

The end story is that we would rather implement a practical overclock around 3.8GHz with the i7/860 or i5/750 at 1.275V than push to speeds around 4.1GHz~4.3GHz that require more expensive memory kits and cooling. In that context, the ASRock board is more than capable for most overclocking duties.

ASRock Software Test Setup
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  • Gary Key - Monday, October 5, 2009 - link

    The PCIe lanes coming off the P55 are 2.0, the problem is that they are running at 1.x speeds (2.5GT/s). On these two boards, the x16 slot is off Lynnfield and will not be affected by any card placed in the x4 or x1 slots off the P55.
  • Mr Perfect - Tuesday, October 6, 2009 - link

    I should probably know this, but what does a 2.0 slot running at 1.x speed bring to the table that a 1.x slot doesn't? Does it provide more power or something?
  • MadMan007 - Tuesday, October 6, 2009 - link

    Yes I was half right with my post and nothing Gary said was technically wrong it's just misleading. They are PCIe 2.0 spec slots but running at half speed, this is clear from Intel's chipset disgram. It's really a farce to call them PCIe 2.0 though because the overridingly most important change from 1.x to 2.0 is the double bandwidth, there are other changes like the power rating I believe and maybe some low level changes but nothing major. I think it's false advertising to call them PCIe 2.0 personally because they don't fully conform to the spec.

    In any case I'd still like to know how many lanes the main CPU-based slot retains when a 1x or 4x card is placed in a secondary CPU-based PCIe slot. Anandtech seems to be more receptive to odd little investigations like this so I hope Gary will check it out.
  • james.taylor - Monday, May 10, 2010 - link

    Hi Gary, Thank you so much for this information
  • james.taylor - Monday, May 10, 2010 - link

    again thanks but if you want to buy new memory then http://www.memoryx.net/ this can help you

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