So what really is faster...3.8GHZ CPU but NB at 2000 or 3000MHZ?

[lopri]

Sure, but the bandwidth is just the same:

http://www.madshrimps.be/?action=get...58&articID=926

Check the Everest chart and compare GD70 to the M2RS in the 3.6G test setting. 600 CL4 beats 800 CL7

Yes, but because at that point the bottleneck is NB. It's my hypothesis that when NB is a bottleneck (i.e. NB frequency < 2 x memory frequency), higher memory frequencies are somewhat wasted. When you run Everest, keep an eye on memory read bandwidth and L3 read bandwidth. You will see both of them moving together very tightly. It seems to me, NB can only process as much as memory can feed it, and memory can send data only as fast as NB can process.

My hypothesis is in the post #27 and #28 in this thread. In your testing, if NB was clocked @2.8GHz, DDR3-1600/CL7 would be pulling ahead, leaving DDR2-1200 behind.

You can see it from Tony's first post in this thread. In the encoding test, look where the performance stops improving with DDR3-1333, yet keeps improving with DDR3-1600. It's somewhere around 2700~2800MHz NB. So DDR3-1333 is good enough to feed 2600MHz NB, but going higher you'll need a comparable (good timings) DDR3-1600 to keep the linear scaling.

So depending on applications - some apps will need to access system memory more often and others don't - NB frequency and memory frequency both matter, and ideally you'd want to have enough memory bandwidth for your NB even if some of it is wasted. If your NB doesn't clock any higher than, say, 2400MHz, then DDR2-1200 or DDR3-1333 will be all that's needed.