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Guest rdg

Need some help on FSB and Ram speed

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Hi,someone brought up the point that FSB and ram speed need to match. Ok, I bought my system and the first thing I did was OC using AI Overclock built into the bios. The original bios I was using would only OC to 5%. When a new bios was released and installed I was able to OC to 15%.Now I am running 3.45 or so and it is stable with FSX. I am not a guru but I would assume that when I did the AI overclock the ram had to be adjusted as well. Since AI Overclock adjusts speed based on load, I ran Prime95 to load up the system then ran CPU-Z to see the details. My issue is I dont understand the numbers to know if everything is right. Memory is: pc2-6400 - 400 mhz x 4gigProcessor is: QX9650Here is what I see in CPU-zProcessor>> Core Speed 3451 Mult 9 Bus Speed 383.5 Rated FSB 1533.8Memory>> DRam Freq 460.1 --- I did not list the timings (do you need to know these?)Any clarifications or suggestions would be much appreciated!!RegardsBob G

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BobYes your PC's mother board has overclocked your memory too.....you should be OK but run Prime95 for a while to verify your DDR isn't failing @ this increased speed.CPUZ is telling you your CPU runs @ 3451 MHz, the CPU multiplyer is x9, the FSB runs @ 383.5MHz and DDR runs @ 460.1MHz (920.2MHz effective assuming DDR2 is used).Your DDR is rated at 400MHz, but as you have discovered will run @ slightly higher speeds.On Intel boards, the FSB speed is linked to the DDR speed - so if you overclock the CPU (only way to do this is increase FSB speed), DDR is overclocked also.Is a QX9650 CPU an extreme edition? If so the multiplyer should be unlocked and adjustable up to its max (allows more settings available for stable overclocking).You should be OK with small FSB increases, but if you're into extreme overclocking then you will have to reduce the memory multiplier (not the CPU multiplyer) and timings (eg from 4-4-4-12 to 5-5-5-15) to bring the DDR speed down to allow boot up and stability verification.For example my C2D E4400 is overclocked from 2GHz to 3.2GHz.The CPU multiplyer is x10, so I increased the FSB from 200MHz to 320MHz.At the same time this increased the DDR speed, so I altered the memory multiplyer (from 2FSB : 1DDR to 3:5) so that my DDR runs @ 533MHz (1066MHz effective).If I had left the memory multiplyer on auto, I think the DDR would attempt to run @ 1280MHz effective, which will more than likely cause a failure to boot using my OCZ DDR2 which is rated at 800MHz effective.I'm no guru either - check your motherboard's web site & enthusiasts forums for more specific advice.If you've got a good board and good CPU cooler, you'll be able to attain a very good overclock without too much difficulty.Have fun, and watch those temperatures!!RegardsChris

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BobYes your PC's mother board has overclocked your memory too.....you should be OK but run Prime95 for a while to verify your DDR isn't failing @ this increased speed.CPUZ is telling you your CPU runs @ 3451 MHz, the CPU multiplyer is x9, the FSB runs @ 383.5MHz and DDR runs @ 460.1MHz (920.2MHz effective assuming DDR2 is used).Your DDR is rated at 400MHz, but as you have discovered will run @ slightly higher speeds.On Intel boards, the FSB speed is linked to the DDR speed - so if you overclock the CPU (only way to do this is increase FSB speed), DDR is overclocked also.Is a QX9650 CPU an extreme edition? If so the multiplyer should be unlocked and adjustable up to its max (allows more settings available for stable overclocking).You should be OK with small FSB increases, but if you're into extreme overclocking then you will have to reduce the memory multiplier (not the CPU multiplyer) and timings (eg from 4-4-4-12 to 5-5-5-15) to bring the DDR speed down to allow boot up and stability verification.For example my C2D E4400 is overclocked from 2GHz to 3.2GHz.The CPU multiplyer is x10, so I increased the FSB from 200MHz to 320MHz.At the same time this increased the DDR speed, so I altered the memory multiplyer (from 2FSB : 1DDR to 3:5) so that my DDR runs @ 533MHz (1066MHz effective).If I had left the memory multiplyer on auto, I think the DDR would attempt to run @ 1280MHz effective, which will more than likely cause a failure to boot using my OCZ DDR2 which is rated at 800MHz effective.I'm no guru either - check your motherboard's web site & enthusiasts forums for more specific advice.If you've got a good board and good CPU cooler, you'll be able to attain a very good overclock without too much difficulty.Have fun, and watch those temperatures!!RegardsChris
Thanks Chris. I am only using the AI overclock feature. No way am I going to attempt to do this manual. I just wanted to make sure everything looked OK. Thanks again for your help on this and taking the time to look at my post.RegardsBob G

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