One further comment on the PSU:
Isn't it incredible how crummy they can make a PSU? There are many things that contribute to the stability, or lack of stability, in a computer. But the PSU is very key, especially the regulation and current capability of the 3.3v rails.
Even 500 watts is not enough if it cannot furnish enough current on the 3.3v line. Some of them send the bulk of the power through the 5 and 12 v rails. Likewise, even a 200 watt PSU can be adequate for many lightly-configured AMD systems if the current capacity exists on the 3.3v rails.n Gatting a solid 300-400 watt PSU from Sparklepower, Antecs TruePower, Enermax, or PC Power and Cooling makes a big difference, especially if the unit you have now is even standard, let alone substandard.
Anyway, a crappy PSU will give you absolute fits to the point where you are diddling with your memory timing, adding cooling fans, upgrading heatsinks, all kinds of crazy (and fun sometimes) stuff that is often not needed with a solid PSU. I have known many people who go out and buy new memory, etc... before trying a 'real' PSU.
It's very much overlooked in most systems. Not as glamorous as a nice vidcard or slot-load DVD reader
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Oh well, I'm done cranking about the typical PSU now.