I'm running a Abit an7 nforce2, a gig of corsair xms c2 ram, and that amd athlon 2500+ mobile. It runs stable at 333 fsb but every time i try to kick it to 400 fsb the ram shits a brick, or so it seems. Can anyone figure out what this problem is?
Some people have reported problems with the AN7 and Bartons when it comes to OCing. Can't say that it is anything in particular, as your setup looks solid for some good Ocing. Could just be bad luck. You can get some serious discussion on Abit's Forums. You might be able to get more specific help as well.
Offhand, I would think perhaps your RAM or chips aren't getting enough voltage, or perhaps you need to lower the multiplier on your chip to go higher on the RAM.