Windows 2000 not recognizing ram

I just did a clean install of Windows 2000 pro on my system. I have 640 megs of ram broken up into two 256 meg sticks and a 128. The 128 is new and not recognized by the OS, though CPU-Z does recognize it. The 128 stick is pc 2100 while the other two are pc 2300.

I'm not sure why windows 2000 won't recognize it. I'm not getting crashes or anything (as I would expect if the ram was bad) the OS simply doesn't think I have anything but the two sticks of 256. Any ideas?

Computer is self built for the most part.

Intel Pentium 4 1.8gig
640 megs of ram (512 recognized)
geforce fx 5200 128 meg vid card

Please let me know if I need to provide more information.

 

You didn't specify whether the slower ram was added before or after the reinstallation of Windows. If you had the faster ram before, and added the slower later, then it wouldn't be recognized.

Pull the case cover off your computer, turn the power off from the source ( outlet or powerstrip ) ground yourself against the computer case by touching it to prevent static discharge, and remove the 2 256 meg modules. Leave the 128 meg module installed, turn the power on and boot your system. Let Windows fully boot, and then turn the system off. Unplug from the power source, touch the case again to ground yourself, and reinstall the 2 256 meg memory modules. If Windows boots, it should run all your ram at the slower rams speed, if this doesn't fix your problem, please post again!