I've got a MSI kt4a ultra version 1.5 (latest).I checked and double checked that i could put in a 3000+ (333 fsb)amd in it as an upgrade,on the MSI web page and it said my board was compatible.I looked at the setup instructions,it just says its automatic,great i thought. So i've put it in,its runnig fine,but it won't go any higher than 2200+ (1.7)My old one is a 2400+!!
I don't know about your particular motherboard, but I had a problem with getting an Athlon 2500 up to it's full speed on an ASUS mobo. Solved by getting some decent memory from Crucial instead of unbranded. Have you upgraded the memory? Do you need to update the BIOS?