何必在电源上省钱

AMD Phenom 功耗在95W~125W. Intel Core 2 Quad power consumption is also rated at 95W.
Adding HDD, mobo, DDR2 RAM, video card, it's recommend to use at least a 400W PSU.

PSU is probably the last place to save money. Junky PSU can easily destroy your CPU and mobo or quit working after a few months. A good quality PSU is only around $30 these days.