RAM - why anything other than 1:1

[aesmith]

Hi,

All the overclocking advise suggests running RAM at 1:1, same speed as the FSB.

So as I understand that, for a stock Q6600 that means 266HMz and DDR2-530 memory. Is that correct, or have I missed a divider or multiplier somewhere?

Assuming I'm right, my question is really why do manufacturers recommend faster RAM? For example for my Asus P5Q Pro the recommended memory is DDR2-667, 800, 1066 or 1200. As far as I can see no supported processor would need an FSB of greater than 400MHz, so you'd never need more than DDR2-800 for a 1:1 rig.

If you run the RAM faster than 1:1, which actual processes would benefit? Not transfer to/from the CPU, I assume. But does graphics or I/O perform faster?

Thanks in advance, Tony S

 

[m_silkstone]

1:1 is just for stability and most people recommend doing this by raising the fsb and lowering the multiplier.
I believe it's for faster communication between your CPU and Ram. Remember the ram doubles the FSB but the CPU quadruples it. So ideally for best results on a stock Q6600 you'd have a 266FSB, 1:2 ration on ram, making it 1066mhz, and your cpu's FSB would be 1066mhz

 

[aesmith]

OK. So in your example we'd have ....
FSB = 266MHz
CPU = 266 x 4 = 1066 = stock Q6600 default speed
RAM = 266 x 2 x 1:2 ratio = DDR2-1066 speed

In that configuration would the RAM talk to the CPU at a higher speed than 1:1 RAM would manage?

Tony S