Could also be your video card overheating. A lot of times when a video card overheats it will freeze the screen or turn the computer off. If your card has a fan on it try putting some thermal compound on it to help dissapate heat. It will probably shut down a lot more if you play video games on it.
you'd have to get a more powerful psu if you want to rule this out. if you think the 450w isn't providing enough power testing a 300w isn't really narrowing the possibilities
it also depends on the quality of PSU. if you get a cheap PSU that says max [something] Watts, then chances are, it usually doesn't give that.
you'll want a PSU that can constantly output what it's rated at, not just get that occasionally
Isn't that 2900 an unusual configuration? I think Tigerdirect was selling these, but some were having issues? I recall that AMD "special made" these for someone. Perhaps someone with a better memory can expand on this.
yah it ends up that it will only work with a specific HP mobo so i tryed a different Cpu and it works great now(slower but great) so that means i need to break down and buy a new cpu fun stuff