I just put an old Barton 2500 back online on a duallie Asus AMD board and I was scrating my head as to why, with my normal board mod (solder the multi on the rear of the board) it wouldn`t boot.
No cmos kill on these things but I eventually got it going and found out the reason.
CPU0 was OK but CPU1 couldn`t make it`s mind up whether it wanted to be a 2200Mhz or a 5000Mhz cpu. I just wish it would have run at 5000Mhz, I could have got quite a few grand for it on Ebay
Anyway, on further investigation, it appears the internal frequency is wobbling all over the place if it`s on 133Mhz FSB but settles down to a saner 2222Mhz at 100FSB.
So now, instead of 2 modded 2200Mhz Bartons, I`ve got one 2200 and one 5000 which gets pulled down to 2222 if I run them both at 100FSB which then gets the good one to 1600. Only the Asus would run 2 totally different speed cpu`s and let you get away with it.

Anybody else had anything similar?