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Questions Involving OCing i7 920 to 3.66

Last response: in Overclocking
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May 24, 2010 9:10:15 AM

Hello. I’d like to preface this by stating that I’m not here without any knowledge, begging for someone to tell me what to do. I’ve read a number of guides on overclocking, but still want to discuss the process with my hardware specs in mind and ask a few questions.

My goal is a moderate but non-trivial overclock of an i7 920 processor to 3.66. I’ve been collecting the parts over the last month and will begin the building process in about two weeks. I understand the risks involved. As such, my approach is to be very conservative in my incremental changes. Here are my specs:

CPU: i7 920
Mobo: Asus P6X58D-E
RAM: 4GB Corsair XMS3 1600, Cas Latency 9, CMX4GX3M2A1600C9
PSU: Corsair 850tx
CPU cooling: Xigmatek Dark Knight S1283v
Case: Cooler Master HAF 922
GPU: EVGA Geforce 470
HDD: Western Digital Caviar Black, 750 GB, 7200 RPM, 32 MB
OS: Win 7, Home , 64 bit

The process, as I understand it, involves incrementally increasing the BCLK to 183 with a multiplier of 20. The multiplier on the RAM should result in a clock speed significantly below 1600 for now and the multiplier on the QPI should be 2x or 2x+1 the RAM’s multiplier.

Using realtemp, prime 95, and CPU-Z, I need to start with modest overclocks without increasing Vcore. CPU-Z confirms my settings. Realtemp measures the temperature. I generally don’t want these to be above the low 70s at full load. Prime95 employs stress tests to confirm processor stability. At first, there is no need to increase voltage. Don’t do this until the system is unstable due to insufficient voltage.

After this, I need to modify the RAM multiplier. Since RAM OCing is a significant contributer to instability with only marginal benefits, I plan to leave the clock speed at the maximum sub-1600 mark. QPI will be adjusted to 2x this or 2x+1 this.

Once this is all done, I plan on running Prime95 for 24 hours to guarantee system stability.

Question: Is this correct? What am I missing? What did I get wrong?

Question: What’s the effect of having a 2x versus a 2x+1 QPI multiplier of the RAM?

Question: At what increments should I overclock? Keep in mind that I want to be conservative and play it safe. At what increments should I increase CPU voltage?

Question: How long should I run prime95 at each increment prior to the last?

Question: What is CPU PLL Voltage? Is it necessary to modify this? If so, how should I go about doing this?

Question: Voltage settings on RAM and QPI concern me. While most guides clearly explain how Vcore must be increased proportional to the processor speed, that sense of proportionality is often lost on the analysis of Ram and QPI voltage. Where do they start? In what increments do I want to increase them? When do I want to start increasing them? What are unsafe levels?

Question: If I run into a technical problem, how do I isolate the cause? How do I distinguish if the problem is due to too little CVOLT, QPI volt, or RAM volt?

Question: Will future upgrades to the RAM or the GPU affect my overclock in any way? I plan to upgrade to 8 GB of RAM total (same model) this winter and eventually run a two way SLI configuration when the price of the 470 eventually drops.

My thanks in advance for any help.
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a b K Overclocking
May 24, 2010 2:54:29 PM

3.66 is a modest goal. I would guess that you could set your motherboard to that setting, set the ram multiplier to maybe 8:1 off the top of my head, set the PCI to 100MHz max., set the QPI, and go. Personally with a good motherboard and good cooler I don't think you have to work up to that speed in small increments. If you feel that you do want to work up a little bit, start at maybe 3.4GHz, then 3.5, then 3.66. You should not have to change any voltages to get this to work. If you wish, after you get it working you could try reducing the voltage a bit to control the heat and power usage. Certainly watch your temperatures while you do this. With that cpu and that cooler you will not have temperature problems if the cooler is properly installed.
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