I would be VERY surprised if it was your PSU holding you back. To find out if it is or not, get a cheap digital multi-meter and put the probes into a molex plug (preferably +12v and ground) while running 3DM06. If you see a big voltage drop just before it crashes (eg if the voltage drops to like 11.0v or lower), then it's your PSU, otherwise, it's most likely instability elsewhere.

Eller