Stumpjumper5200 said:
Well you can't even compare Dual Channel DDR on P4's and AMD's, because the AMD's don't have anywhere near the kind of bus bandwidth it takes to utilize a dual channel setp.
But anyway, I'm running a dual channel setup on my system (in sig). At 166fsb with really slow timings (my memory is kinda cheapo ) I get a bit over 4GB/sec of memory bandwidth in Sandra. I think it's about 4050MB/sec.
Can't wait for my 1 gig of Corsair XMS to get here!
What ratio of memory to fsb is usually used for P4? What fsb and memory speed are you running at? What is the max fsb for P4?
I know that in absolute term, Intel P4 has a much higher memory BW than AMD nforce2 dual channel.
Assume P4 max at 166 fsb, max BW = 166x4x8 = 5300 MB/s. While AMD nforce2 fsb max at 200 MHz, and max BW = 200*2*8 = 3200 MB/s.
I am try to compare the memory controller efficiency between Intel P4 and nforce2.
Since you run 166 fsb, the maxBW = 166x4x8 = 5312 MB/s and you are getting about 4000 MB/s. So do you agree that P4 memory efficiency ~ 4000/5312 = 75%.
For nforce2 whose absolute BW is much lower than P4 chip set. But I estimate its dual channel memory efficiency ranges from 50%-80% too. 50% is when running dual channel SYNC, since half of BW is wasted. 80% is when fsb is running much higher than memory speed (using slow memory).
E.g. fsb = 200 MHz, memory speed = 150 MHz, the dual channel effective BW ~ 2900 MB/s. So nforce2 memory efficiency = 2900/(2400*2) = 60%
fsb = 200 MHz, memory = 100 MHz, effective BW ~ 2400 MB/s. Efficiency = 2400/(1600*2) = 75%. It is more efficient to run at slow memory, but of course the actual BW is much lower.