I just replaced my 2000+ that would do 2Ghz with 1.8 volts and 200 FSB with this same MB, but as soon as I swapped in the new 2500+ I can't use the 200x10 setting with the Agressive CPU setting. On the 2000+ I could, but I am forced to Optimal to get 2Ghz. I can, howver run 200x9.5 with Agressive, if I try 200x10 the screen goes off, then comes back on, and the speed does as 1100Mhz or something. Any ideas? I have the May BIOS.