Ok, im running windows Vista and for some reason, my computer will lock up and restart at random times. Now it only does this when I have both sticks of ram in. I run 2 sticks that are 2 gigs each (Patriot PC-6400). Any idea on what the problem could be? I'm running them at 2.0V

What is their spec voltage (it is often printed on the stick itself)? If you DIMM/memory voltage is set too high or too low, they may not work correctly. There might also be a defect in one or both. Try running memtest86+ (freely downloadable as a bootable floppy or CD image) through at least a few complete passes and make sure there are no errors.

Well I did the vista memory diagnostic and it came back with no errors. It doesnt seem like an error with either stick becuse it runs fine with either stick in. The memory has 2.0V written on the sticks.

No ideas? I've bumped it up to 2.1 V as someone told me but it will still crash with both sticks in, yet does not when only a single stick is in.

The Vista memory diagnostic isn't adequate. Use memtest86+, and if that runs through at least 2 full passes without errors, run Orthos (or similar PRIME95-derived stress tester) in "blend" mode for at least a couple of hours without errors. If you get errors, something is wrong with the RAM or MB or the settings.

I downloaded the files to create a bootable floppy with it on it, but i'm running vista 64 bit so I cant use it...

Why can't you use the floppy? I have no experience with Vista 64, but I can't see how it would prevent you from using Memtest86.

Make sure BIOS sees the floppy before the hard disk in the boot sequence. Memtest86 doesn't need an OS - it is a standalone program. Run Memtest86 with only one DIMM installed - make sure you test both DIMMs individually. Then install both DIMMs and test them together. Let us know the results.

Did you try the DIMMs in other memory slots?

If you're having trouble making a bootable floppy, you can also download the bootable CD image version of memtest86+.