So hey, in the morning I tried to turn on the desktop and instead of turning on immediately like a good boy, it took about 30-40 seconds after pressing the power button before it finally lit up. No me gusta. Well, whatever, a bit of morning webbrowsing and I turned it off and went to work. Now it just won't start at all - no reaction after pushing the button, or any later time. I tried fiddling around with the cables, switching plugs and sockets, alas nothing.
So, are these common symptoms of a failing power supply, or could something more sinister be afoot? Is there a way to test it?
I'll probably be buying a new desktop around christmas, with a new monitor and all, but it's still extremely annoying to rely on a very crappy headache-inducing laptop I'm using to type this. Not to even mention the hard drives.

The power supply is a Chieftec 450W - more than sufficient for a GeForce 8800 GTS 512 that I've had, and loved, for a couple of years now.

usually powersupply problems we will see in some game. With my atis 6850 asshole, I have to underclock that a bit otherwise it works just fine. So as I answer to your thing.. You need 2 nirnroots smashed in impstools. That doesn't help in your machine but you are relacet and you make thins work.

When you say light up, you see 0 activity or does it at least boot/beep and then do nothing? If you literally don't get the lights to show up, then its the power supply I think. Perhaps the motherboard, but probably the PS.

You said it took a while to boot; after it did boot did you notice any odd behavior during the time it was on?

I get no reaction whatsoever after pushing the button. Yeah, the thought of a busted motherboard crossed my mind. I'd really like to have that ruled out. Nope, it ran perfectly fine. I dicked around with it for an hour or so, turned it off and left.

Wouldn't at least the power supply's fan run if the issue was a busted mainboard? Or is even that fan controlled by the mainboard in your setup?

Uh. I'm not sure. Doesn't it work like that everywhere?

Does your computer make any noise at all after you press the power button?

Here's another thing to try if all else fails. Try replacing the coin battery on the motherboard.

Turns out it *was* the PSU - shortly after my last post I just went ahead and bought a beastly 600W OCZ I would've bought sometime in the future anyway, and installed it an hour ago - worked without a hitch!
Thanks for all the replies. Yes, even the one about nirnroots. I'll mark the most, uh, advicey post as the answer. Cheers!

I thought it was the PSU

Good to hear that it worked out. Its abit annoying when the computer decide to not work.