Came home to find machine down (yeah, i left it on crunching BOINC / Seti@home data. I have AC, tho, and the room was cool...).

Power up. No POST, no video, no beeps, no luck. Fans spin. CDRom powers up. HDD seems to power up (casing vibrates a lil').

Reset CMOS (it's a 'use the jumper' board, an old KT333 Soyo Platinum Dragon. yeah. i know. don't laugh ). No joi. Took out the battery for a few mins. Nada.

Powered down and unplugged, and took out everything - GPU, sound card, HDDs, CDROM, RAM, everybody out of the pool. Plugged in mobo with only CPU and its fan powered (well, the northbridge fan and a case fan i couldn't detatch, as well ).

Nothing. Lil green "mobo has power" LED is on, fans spin, but no beeps. I stare at it a few minutes. Inspired, i touched the CPU heatsink carefully -

stone cold!

This, i assume, is very very bad. Either the CPU is not getting power (I don't see how - it's an AMD 2200+ and there is no connector on the KT333 for the 4-pin i can see, the 24-pin is the only power connection i know of) or... it's a coaster. A very small coaster. With spikes on the bottom.

Is this the most likely assessment?

TIA and kind of hoping i'm wrong,

Rob

PSU?

That seems like suspect #2; however, the board is getting power and the fans spin, drives spin up, etc etc - seems like if the CPU was getting *any* power, it would heat up a lil after 5-10 minutes, wouldn't it?

Or could the PSU fail in a way so as to not power the CPU while powering the other board components..?

The PSU can do strange things. I had to replace mine recently. I would boot up my computer and some times the whole thing would all of a sudden shut down. I noticed this happened more when I tried to play a game and the video card kicked in and drew some more power. The computer would work most of the time but like I said every once in a while it would fail. I replaced the PSU and now I no longer have that problem. I would say it is your PSU as well.

check the capacitors on the board. they should be flat on top without any trace of leaking..

I believe this is going to be your power supply as well. If it has more than one 12v rail. it sounds to me like one of the rails has failed. and this is why the fans work. you can check this easy by unplugging power supply from everything but hard drive and put a paper clip between a black wire and the green wire on your mother board connector. then you can check the voltage with a meter on all the pins.

follow this http://pinouts.ru/Power/atx_v2_pinout.shtml if it is a 24 pin board and if it is 20 pin follow this http://pinouts.ru/Power/atxpower_pinout.shtml

I have had this problem before. And as a electrician I can tell you that just because it has voltage dose not mean all is ok. need to smell power supply and if you smell anything burned replace.