Importance of dual channel memory for dual core processors

[patrik]

I just swapped memory between my two Core 2 Duo processors:

E6600 (2400 MHz) dual channel    896K fft 23.5 ms
E6600 (2400 MHz) single channel  896K fft 32.6 ms
E6600 (2400 MHz) dual channel   1024K fft 26.0 ms
E6600 (2400 MHz) single channel 1024K fft 36.6 ms
E6300 (1860 MHz) dual channel    896K fft 29 ms
E6300 (1860 MHz) single channel  896K fft 35 ms

Earlier it has often been true that the effect of faster memory on Prime95 was marginal. But here it would be worth the money to buy a second memory stick to the computer running only single channel.

(The fast computer is running one 896K FFT double-check parallel to a 1024K FFT double-check. The slow one is running two 896K FFT double-checks.)

Specs: E6600 on ASUS P5W DH Deluxe. E6300 on ASUS P5LD2 SE, Rev. C. All memory 667 MHz Kingston KVR DDR2 non-ECC. All default, no overclock.

If you own a dual core computer and have similar comparisons, please post!

[db597]

That's a dramatic difference. Looks like there was a shortage of memory bandwidth to feed both cores at the same time. I've not tried it on mine - have a Pentium D 930, but it will probably not be so dramatic since this is a significantly slower cpu at Prime95. Indeed, the performance gap between your E6300 and E6600 is much less.

[olmari]

On the nForce2 dual-channel dual-channel was still half artificial thing as CPU itself didn't have any clue about dual channels etc, but on 64-bit AMD (I'd imagine Intel too) computers has native dual channel memorycontroller and whole architecture of system can utilize it, compated to nForce2 where it was only south+northbridge that could benefit from it.

[E_tron]

Thanks for pointing out the difference. It sounds like fast DDR2 may increase performance even more!

Originally Posted by olmari

On the nForce2 dual-channel dual-channel was still half artificial thing as CPU itself didn't have any clue about dual channels etc, but on 64-bit AMD (I'd imagine Intel too) computers has native dual channel memorycontroller and whole architecture of system can utilize it, compated to nForce2 where it was only south+northbridge that could benefit from it.

nForce 2 is/was a nice chipset. I still use it in my primary machine; it has that nifty SoundStorm audio processor. I don't think nVidia will bring it back either .

note: nForce 2's dual channel is useful when one has a hand-full of slow, cheap memory. So, a processor can run at 400FSB and dual channel DDR266 without performance hits.