Thanks, I have 2x2.66 quads but can only hit 9500. I think this may be due to my memory config. I have 2x4GB dims in the top riser and 4x1GB in the lower riser. Any views?
I remember that i read an extensive article regarding that topic, but can't find it right now. Conclusion in a nutshell (from the top of my head):
The sweet spot is to have two matching FB-DIMMS in the upper and 2 matching FB-DIMMS in the lower riser.
Reason is that with less slots populated you miss out on the amount of Ram available and with more slots populated the RAM latency increases too much (inherent problem with all FB-DIMM's), thus effectively impairing your system performance.
Another thing to look after is the rank & organisation of the module - some are said to be faster than others (sorry, i'm too tired to google it for you). Can't tell whether that is an urban myth, though.
With the abovementioned population (2 upper, 2 lower) you can theoretically also get quad-channel iirc, but i can't remember whether you need to have 4 identical DIMM's or if it is sufficient to have 2 pairs per Riser. And the effect on real-world performance is disputed.
As comparison: I have a pair of 2GB modules and a pair of 4GB modules (= total of 12GB) on a Dual-2,66 MP1,1 - ran a quick Geekbench 32bit (free) test and got a total score of 5146. That is with EyeTV, Firefox with over a dozen tabs, Safari with 3 tabs and AppleMail all running in the backgorund (plus a dozen smaller tools and programs).
Edit: Forgot the memory scores, so i did the test again, this time with no big programs running and after a fresh reboot. Total score: 5574, mem performance: 2200, mem bandwidth performance: 1848.
