I used to skimp on the PSU and buy 30 quid 650 watt efforts from my local pc shop, but they really are a waste of time and money, when I blew my 3rd 1 in about as many months I came to my senses and not wanting to destroy any of my more expensive components I splashed out on a half decent PSU and it has been great for the 4 or 5 months I have had it, GPU gets the most spent on it but if you skimp on the PSU you really could be open to a multitude of problems, not just blowing it up and potentially frying more expensive components, but you could have lock ups, crashes and BSOD`s simply by having a poor PSU.