Cheers for the prompt reply. Please keep us posted on your success/failure.
I just bought one today too (X2 3800+)
I still have to find a good time to shutdown the box and pull the darn thing apart. My unit usually runs 24/7 so I'm not too sure when I'll get the chance yet. I'm not fond of the qbic setup as far as cpu changes go - very time consuming (disassembling & re-assembling far too much).
p.s. I'm assuming you've done a decent memtest stress test on the system (before you started installing Windows). I've been caught out by incompatible memory (or bios memory settings) before - it was actually when I first got the eq3901.