In my amateurish, fumbling way I've been steadily trying to twist a little prebuilt HP slimline into the shape of a passable budget PC. The motherboard, CPU and RAM are about the only original components remaining to it.
After swapping the processor for one which is, according to the manufacturer's website, supported by the motherboard: I get fans spinning, no POST, no beeps (though I'm not sure I trust the buzzer, it was beeping randomly for a few months before it shut up; it may be dead), no display (from either the GPU or integrated graphics).
There are no bent or missing pins that I can see, though they were a bit linty since the processor arrived from eBay encouragingly wrapped in toilet paper.
I looked for a newer BIOS but found nothing. The other components are working. I tried clearing the CMOS to no effect. The old processor still worked as normal when I put it back in, so I've managed to avoid destroying anything in the intallation procedure.
So my guess is either the BIOS needs updating (but I can't find one) or the CPU's dead (but I have no way of checking). Are these good guesses? Is there an obvious solution?
specs:
Pegatron M2N68-LA (Narra 6.01) BIOS v5.04
Athlon II X2 215 / Athlon II X4 640
3GB RAM
GTX 550 Ti
120GB SanDisk SSD PLUS
320GB HDD of some kind
EVGA 500B PSU (500W)
Windows 7 Home Premium
http://www.support.hp.com/us-en/product/HP-Pavilion-Slimline-s5000-Desktop-PC-series/3999463/model/4032748/document/c01866567/