Here's a little teaser....

[Opteron146]

... this memory worked fine in the Quad FX

Do you mean the L1N64 from Asus ? Then no wonder that nothing is working. You have unbuffered RAM, which wont work in KFSN4-DRE. Get yourself some nice registered RAMs. There are new DDR2-800 ones from Kingston around. Type No. is: KVR800D2D8P5/1G.

@xPliziT:
If your programs runs very well on recent Athlon64s and not that well on Intel chips, then I assume that it is due to heavy use of FPU code instead of SSE1/2/3. As there is no FPU improvement in Barcelona your code might run slightly better because of the bigger caches, and better prefetchers, but performance will be hurt badly because of Barcelona's current clock disadvatage.

cheers & good luck

Alex