When I found myself with a similar dilemma a few weeks ago, I was happy that the motherboard was faulty as the multimeter readings for the PSU were fine and it powered a hard drive, fans etc perfectly well when not connected to the board. It was also a reasonably expensive item even if not quite up there with yours.
However, I decided that I couldn't be sure, and as I hadn't done any PC building for ages I bought a new motherboard/CPU/memory and a new PSU. The old CPU was an early i5 and as compatible second hand motherboards are stupidly expensive, I couldn't reuse it.
I was then left with the old PSU which I used to build a second PC/Server using an old Athlon 64 and motherboard from the I-can't-throw-that-away pile. I learned a lot about the fibs told by Nvidia and several mobo manufacturers about how much memory the early Nforce chipset/bios combo could support (up to 4GB but only if you could find memory modules that nobody actually made) and had fun playing with it until it started making crackly noises and finally the PSU burst into flame with a loud bang.
So my present theory is that the PSU may well have killed the original motherboard by serving up generous portions of voltage at inappropriate moments.
Of course, I then decided to buy an ultra cheap PSU and discovered that I could make use of my old i5 and memory with a new motherboard from Gearbest who manufacture a whole range of boards based on old chipsets for a far more reasonable price than second hand ones fetch on ebay. Expensive things computers.never trust a man in a blue trench coat, never drive a car when you're dead |