Overclocking a Q6600 with PC2-6400 RAM help!!

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yahkouh

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Jul 23, 2007
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Hey everyone, I'm new to overclocking and need some serious guidance!

I'm thinking of purchasing a q6600 with the new G0 stepping but I have some overclocking questions. First, I already purchased 2x1gb OCZ DDR2 PC2-6400 RAM and I'm not sure what numbers to try for overclocking. I've been reading that it is good to have a 1:1 ratio for RAM and cpu FSB. This would be fine for me if I could overclock to 3.6ghz (9x multiplier and 400mhz FSB) but I really doubt that I'll be that lucky. So instead I'm hoping to hit at least 3.2ghz but then I'd have to use an 8x multiplier with a 400 FSB to get a 1:1 with my RAM. But I hear it is better to use 9x multiplier at lower clock than lowering the multiplier with higher clocks. If this is the case, for around 3.2ghz, I would need 9x multiplier and a FSB of 355mhz. So in this case, would it be better for me to lower my RAM speed to match that of the cpu FSB to hit the 1:1 ratio? Or should I just leave it at 400 no matter what?

I guess my main question is, how important is it to have a 1:1 ratio between CPU FSB and RAM? Does it hurt to have the RAM faster than the cpu FSB?

Thanks everyone in advance.
 
It's much more important to maximize your CPU clocks than to get a 1:1 with memory (within limits.) If it's 3.2Ghz and maintain 1:1 or 3.4 and have 5:4 or 4:3, I'd say go for the higher CPU clock. There are any number of benchmarks and articles on this topic if you feel like researching it. Even artificial benchmarks rarely show the benefit of higher clocked memory on the Core 2 platforms - only a few like SuperPi show even a little improvement. Try and find your maximum CPU clocks first with very loose memory settings / timings and then find the closest reasonable cpu / mem clock multiplier compromise that allows you to tighten up the mem.
 
On boards with the Intel P965 chipset, using 400 x 8 was usually your best bet when running at or around 3200 MHz. The chipset timings change when the FSB goes 1 MHz beyond 400 MHz which really kills performance but I don't think the new P35 chipset has that problem.

Once you get your new system put together do some benchmarking. A new G0 Quad might just be able to run 3600 MHz at close to default voltage with a good air cooler depending on your room temperature. You won't know for sure until you try.
 
Thanks for all the info guys. Also, although the ram has 5-5-5-15 timings, is it still possible to tighten these from my motherboard? Or is the 5-5-5-15 timings mean that it is definitely unstable at lower numbers?
 
It never hurts to experiment. I had some CL5-5-5 that was rated at DDR2-667 and with a little extra voltage it could run stable at CL4-4-4 at DDR2-944. It all depends on what chips the manufacturer used on the module. I find about 2.15 volts to 2.20 volts is a good safe place to run all DDR2 memory. Good D9 Micron chips will go a little higher yet but personally I think you start to lose long term 24/7 stability if you get too carried away with high voltage.
 
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