richmo11 :
Most of the guides have fsb recommendations that are below the minimum my BIOS says I should input, BIOS says minimum 500 yet my multiplier is 9 - I'm confused =/. Also my RAM sticks say 5-5-5-18, and most guides say 4-4-4-8 or 12 .Any advice on OC'ing this setup would be great.
Thanks,
Rich
FSB:
The 680i BIOS work a little differently from the Intel P45 BIOS. With the 680i BIOS, you change the FSB clock, not the FSB freq.
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Definition time (attention purists, I'm talking about DDR2 and I'm simplifying a little
):
Core2 CPU's use a frontside bus (FSB). The FSB is a
thing with two main characteristics: speed which is usually defined in MHz and width which in the Core2's is 64 bits wide. We are concerned with the speed.
Using the Q6600 as an example, the FSB
frequency is 266 MHz. The matching DDR2
memory clock for that frequency is 533 MHz (266 X 2). DDR2 memory transfers two chunks of data for each bus cycle, hence double the frequency. So, to run 1:1 at an FSB of 266 MHz, we need DDR2-533 RAM. What CPUZ does is a little confusing. It will tell you that the memory
frequency is 266 MHz for a 1:1 ratio.
The FSB
clock is 1066 MHz (266 X 4). The bus is "quad pumped". It transfers 4 chunks of data into and out of the CPU each cycle. So each FSB cycle generates 4 FSB clocks.
Now, if you increase the FSB frequency to 333 MHz, the corresponding memory clock is 667 MHz and the FSB clock is 1333 MHz.
I always run my memory at 1:1. That is the FSB freq to mem freq ratio of one to one. That means that the memclock is twice the FSB freq. It's a little confusing. Running memory slower costs performance. Running memory faster does not give you much if any real world performance increase and it can lead to higher instability.
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Any Q6600 will run at 3.0 GHz with the stock cooler. So you want to set the FSB clock to 1333 MHz. You should see 333 MHz in a window somewhere. Then set your memory to Linked. That will put your memory exactly instep with your CPU.
Take your CPU voltage off Auto.
Now try to run Prime95 small fft's to test your CPU overclock. If it passes, great. If it fails, go into the BIOS and increase the CPU voltage 0.1 volt. Retest.
Speeds past 3.0 GHz will require better cooling.
You should be able to get up to 3.3 GHz (367 MHz FSB freq, 1467 MHz FSB clock, 733 MHz memory clock).
While you are doing all of this, you need to monitor your CPU temperatures under Prime95 loads. Stay under 70 C. And do not increase CPU core voltage over 1.50 volts.
RAM timing:
Different chips have different timing characteristics. 4-4-4-12 and 5-5-5-15 are both very common DDR2 timings. Don't worry about variations in the numbers. Lower numbers are faster and more expensive. Core2 CPU's are not affected much by memory timing differences. If you plugged 4-4-4-12 RAM in, you would not notice any difference in performance.