I recently replaced the old athlon 950Mhz on my old system for a new atlhon 1.33Ghz (AMD Athlon 1.33 GHz, 266MHz FSB, 256K Cache Processor - OEM)., but when I set up the bios with cpu freq: 133 and multiplier x10 at 1.75V, the system starts, but win2k fails to boot.
I have an asus a7a266e and 512 mb of pc133 memory. Everything was working fine before the change. The system works well if if I set the freq. on the bios to 1000 instead of 1333.
I checked asus site, and they don't mention any problem with the combination cpu+motherboard.
after your computer has been running for a while, reboot into the bios and go to the hardware monitor(or what ever your bios calles it),from there write down all of the tempitures and voltages and post them here.since you made that big of a jump in speed,your power supply may not be able to power your cpu it also may be a cooling issue.