I just upgraded from my Athlon XP 2100 with 512MB of PC2100, to an Athlon XP 2600 (model 8) with 512MB of Corsair PC2700. After installing the processor and RAM I set the front side bus for 166mhz (since the processor and RAM is 333mhz). I was able to boot up find, but right after POST when Windows was supposed to start loading I got a black screen and my monitor turned off (like my PC was off). So, then I set the processor and RAM for 133mhz FSB again so I could figure out what was going on and make sure I could boot into Windows XP (which I could, otherwise I wouldn't be typing this right now). The processor detects as a 2600+ when I set the FSB for 166 (333), I just can't load Windows and when I check CMOS I see that it is running at 170'F.