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Need help with overclocking memory

Gordon Freeman

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I have two TWIN2X2048-8500C5D's with the optional fan unit for a total of 4GB.

I am running Vista Home Premium 64 bit.

I have an EVGA 122-CK-NF68 680i motherboard.

I have a Q6600 with GO stepping


For about a month when I only had two of these sticks installed (2 GB.), my system has been completely stable with overclocking my Q660 to 2.66 GHz and overclocking the RAM to around 1065 MHz. I achieved this by just going into "Expert" mode in "SLI Ready Memory" in BIOS and increasing the FSB to 1112. Now with 4 sticks installed I haven't been able to overclock the memory at all! If I do not overclock my system, my system seems completely stable. I ran the Windows Memory Diagnostic (it's part of Vista) and set it to "extended" tests and ran it for 9 hours and it detected no memory problems. Even if I just go into BIOS and set the SLI-Ready memory to CPUOC 5%, my system will not boot up but instead, just give a steady beep. I've heard that with all the DRAM slots populated it makes memory overclocking at least a little more tricky such as having to change memory timings and possibly memory volatages. Please help. Thanks.

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When you installed the second set of DRAM, the system's abilities on the overclock was changed due to the on motherboard's memory controller having to now access and load double the slots. You need to manually configure settings that allows the memory controller to access the bandwidth stably with four slots populated. Set your memory to 800Mhz and manually set your timings. Unlink and set the FSB to your overclock.


You can try Linking the CPU:Memory and overclocking the CPU manually. This will overclock the memory controller as well and allow you to very likely access some of the lost bandwidth that the population of four DRAM slots brings about.

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Thanks a million! That confirms what Corsair Tech Support told me about all DRAM slots populated. I didn't realize that before i bought the second set but I'm not disappointed. Crysis ran more smoothly and with no noticeable hesitations to load more level data from RAM as compared with just 2 GB. of RAM. I've done just what you've told me to do in BIOS and my system is stable (passes the NV Memory Test in BIOS at SLOW setting).


My BIOS settings:


Memory Timing Section = Expert

tCL = 5

tRCD = 5

tRP = 5

tRAS = 15

Command Per Clock = 2T


Advanced Memory Settings - All at Auto


All system voltages at default except for Memory = 2.15V


SLI-Ready Memory = Expert

FSB - Memory Clock Mode = Unlinked

FSB (QDR), MHz = 1582 (Translates into BIOS detecting the CPU running at 2.66 GHz)

MEM (DDR), MHz = 919.4 MHz (NVidia Monitor sees this as 920.889 MHz)


I probably can overclock the memory higher and still be stable. With all of the above settings except for MEM (DDR) at 1013.2 MHz, the memory passed the NVIDIA Memory Test at Slow but when I attempted to resume the system from sleep, the system crashed. I then just decided to decrease Memory speed to as close to 900 MHz as possible but still be above that.

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