Author: Frank Stroupe
Intel Core i7 870 LGA 1156 quad-core processor
ASRock P55 Deluxe Intel P55 Express motherboard
Asus Matrix GTX 260 video card
OCZ Z Series 650 watt power supply
Cooler Master Hyper 212 Plus CPU cooler
Ikonik Zaria midtower
Windows Vista Ultimate 64-bit
I had several P55 motherboards to choose from, but the ASRock P55 Deluxe supports up to DDR3-2600 memory, the rest topped out at DDR3 2200 or less. Generally, newer motherboards will end up supporting memory higher than the advertised speed, but you really never know if performance and stability are where they could be. Using the ASRock board not only allows me to run the G.Skill PIS Series memory at advertised speed, it even allows for some overclocking headroom.
Place the memory into the DIMM slots. If you are accustomed to Core 2 or AMD rigs, you will find the proper slots a little strange, with the Intel P55 Express chipset (and the H55 and X58), the memory modules go into the opposite slots from the older chipset, starting with the second slot from the CPU socket rather than the nearest one. All motherboards I have seen up to this point have the proper memory slots a lighter color, most of them white.
You will use the other slots only if using four memory modules. When setting up the new rig, start with two modules first, then add the others after the rig is set up and running properly.
As soon as I installed the memory into the DIMM slots, I knew that the fan was not going to fit with the tower CPU cooler fan in the normal location. Actually it did, but it was only partially in place.
It probably would have stayed in place, but since my CPU cooler is configured to place fans in a push-pull fashion, I decided to put it in a pull position nearer the rear of the case. The Turbulence Fan fit fine then, it locked onto the memory modules with no movement whatsoever. I can’t say that about the other memory cooling fans I have used.
The radiator of the Hyper 212 Plus is not that large. Though there was over 1/2” clearance between the cooler fan and the memory fan frame, I’m not sure if it would work at all with a large cooler, even with the fan on the back side. I didn’t have one handy to check out. Every P55 motherboard I looked at had the same approximate distance between the CPU socket and DIMM slots.
Of course the fan would fit fine using the stock Intel cooler. I’ve never used one so I didn’t have one onhand.
As with all high performance memory, the G.Skill DDR3-2400 will default at a lower speed until the advertised speed is set in the BIOS. This is so that if any additional tweaking has to be done, the rig will still POST. For example, the CPU will normally have to be overclocked to attain DDR3-2400. An “automatic” overclock might not have the VCore quite high enough, or some other setting required for a successful overclock. In that case, the motherboard would not POST. At all. And since memory beep codes are often no beep at all, you would waste time troubleshooting the problem. The only solution would be to first set up the board with a different memory kit that did not require CPU overclocking.
The G.Skill defaulted at DDR3-1600, as I thought that it would. The Turbulence Fan was audible but not loud, I could hear it but it was far from annoying.
Next I went into the BIOS to bring the memory to the advertised speed of DDR3-2400. I knew that there would be some trouble because the processor is not always stable at a base clock (BCLK) of 200, which is what is required to attain DDR3-2400. (which goes back to why memory defaults at a lower speed) First I tried enabling XMP, which increased the BCLK to 200, and lowered the multiplier from 22 to 15. I checked the VCORE, which was 1.3v, and I knew that the auto settings would not work, I nearly always have to have the VCORE well over 1.4v to get stability from a BCLK of 200.
I played around for a while to finally get a stable clock but I finally did.
Overclocking memory is more simple with Intel LGA 1156 (and LGA 1366) systems because the max VDIMM is 1.65v. DO NOT INCREASE THE VDIMM ON INTEL P55 OR INTEL X58 MOTHERBOARDS BEYOND 1.65v!! Higher voltages will damage the onboard memory controller on Core i7 and Core i5 processors. (NOTE—small fractions over 1.65v is ok, I have had boards that would not do odd hundredths and the VDIMM was 1.66v.)
Normally I spend a considerable amount of time looking for the tightest timings by lowering the memory speed. An enthusiast will not be buying the G.Skill DDR3-2400 to run it at DDR3-1333 to get some tight timings. He/she will be purchasing this memory to enjoy some high speed goodness, or for serious headroom for extreme overclocks, so I didn’t bother. I wasn’t able to drop the latency at DDR3-2400, but I really didn’t expect to. I did drop the timings to 9-9-9 and run the command rate at 1T though.
I knew that I wouldn’t be able to find the max overclock on the G.Skill memory due to the limitations of my processor, but I hoped to overclock my CPU enough over a 200 BCLK to show that the memory can be overclocked. I don’t think that I’ve ever raised the VCORE more than about 1.42v on this CPU, but as the old saying goes, you gotta break some eggs. I threw caution to the wind and eventually cranked the VCORE up to about 1.56v, which got me a 215 BCLK and raised the memory to DDR3-2580. This is NOT the max clock of this memory, merely the highest that I was able to overclock my CPU.