Can Generic PSU cause bad OC?

Right now I am running on what is in my sig...but with a generic PSU. My +5 is at 4.68 most of the time, and when I turn on my cold cathode, it drops to 4.65 before my computer freezes. When I unplus everything (3 sunon ultra high speed fans, 1 52x CD-ROM, 1 8x4x32x CD-RW, and floppy) I can get much higher overclocks. Can this be because my generic PSU? Also, if I were to upgrade, what do you suggest I upgrade to? This current PSU is 400W.

I'd say that's what's going on. Just because it says 400W doesn't mean it's an ample power source. You need good combined wattage between the 5V and 3.3V lines. This is where the most draw occurs, so it needs to be high.

You could still go with a 400W, but it needs to be a high quality 400W. I would recommend a Sparkle or Power PC&Cooling. The latter are very expensive, however.

a good 250watt psu, will perform better then a cheap 350watt psu.