I've got an Asus L1N64-SLI WS (not the /B-version), with BIOS 0505. It works nice with an opteron 8214, but I want to use quadcores on it: I have 2 Opteron 8347 HE's laying around.

So I flashed to the official 0506 WS/B-bios using a bootfloppy and afudos. The system still works with the opteron 8214 and regular (non-ecc, non-reg) RAM.
So I tried to put in a 8347 and a stick of DDR2-667 ecc/reg RAM, but the system doesn't boot...

Any idea what's wrong?