GTX 285...How do you overclock it?

I cannot overclock this video card at all using EVGA Precision... I heard you are suppose to do it in increments but I can't even get it to 668 core speed without an eventual crash. I KNOW it is not overheating as it will crash even when the temp is at like 70 and on stock settings it can go above 80 without crashing. Do I have to install an older driver to be able to overclock it or something?

To clarify I am going from 648/1475/1242 to 668/1521/1242. Maybe I should adjust the memory clock as well?

Specs:

i7 920 2.66
6 gigs of RAM
Geforce GTX 285
Corsair tx750w PSU
Windows 7

I'd adjust the memory. I have OC'd 285's well over 700mhz without problems using precision. You might want to check your pci settings in the bios. Try 101mhz, 105mhz, 110mhz. Upping the PCIE voltage up a couple ticks. Try uninstalling precision and reinstalling all card drivers then precision again from fresh download.

You should be able to oc the card better, could be your cpu/ram oc that is messing with it as well. Try all stock settings in bios and then oc the card with precision. Just to isolate the issue.

Chaiyz