BIOS settings for clock speed/multiplier

"There may be nothing wrong with your setup. The external clock to the CPU can be different than the clock to the RAM. I would assume that this is case unless something more definite is listed in your BIOS.

The P4's bus in quad-pumped so you'll sometimes see it's bus speed listed as 400 MHz since it transfers data at the same speed as a a standard 400 MHz bus. So in effect it is still running faster than your PC133 RAM.

Your processors multiplier is locked, it won't respect any change you make in BIOS. So if you try to up your processor bus speed to 133 MHz you'll end up with a CPU sped of 133.33 * 18 ~= 2400 MHz, which is a pretty tall over clock. So what may have happened when you made your changes in BIOS is that the computer failed to boot and automatically reset it self back to safe values."