[pecenipicek]

reset CMOS to default.

It's default.

pop the battery out for a few minutes, and while you're waiting, check the voltage, if it isnt around 3V, replace it. the battery type is CR2032

ive never seen one of those die before the computer became obsolete junk. if it did, your bios would just reset to default every boot and you would get a cmos memory fail message.

i've had two issues with those actually. it might be down to mobo as well, but i know for a fact that until i put in a fresh battery that it wouldnt boot in any case. the second was the "obsolete relatively useful junk" category:p

[TopAce]

I bought a 420 W PSU and built it in. There is power, because the small LEDs on the keyboard flash when I turn on the power supply.

However, the comp still doesn't boot. The sympthoms are the same. I removed the CD/DVD-ROM and plugged in my old video card (this one doesn't even have a separate connector, so its power requirements must be minimal).

Looks like I will have to invest a little bit more if I want to get my comp to work. Next I think I will buy a new motherboard. I checked the Internet for some troubleshooting and found out that some users had trouble booting their systems with the ASUS P4P800 motherboard. Their problems weren't exactly like mine, but the similarities are astonishing. There's the compatibility and money problem though. I looked around and found that the newer motherboards don't have AGP sockets, and my GeForce needs an AGP socket, so I will eventually have to buy a new video card as well. There was only one motherboard that I found to be on sale with a usable AGP socket, but I don't fancy the idea of buying that one MB just because I need an AGP socket.

Also a new motherboard (potentially combined with a new video card) may need more jiuce than the new 420 W may provide, so I may need to buy a new PSU as well. Great. So much for finding a cheap solution.

[LHN91]

I'd drive you out one of my spare P4 boxes with AGP slots I have hanging around, if you lived anywhere near me; I get them for free when the university dumps theirs. Ironically, my old neighbour is running a P4P800, and the issue she has is with the system spontaneously booting  .

The 420w might be enough, if you bought a decent one, and you run a mid-range graphics card. If/when you build, look up psucalc, and punch in the specs. It'll give you a pretty fair idea.

[S-99]

He should be more than good enough with a 420w. Now as to whether or not he's using a $30 paper weight psu for the 420w is the question. Sounds like he has some other system problems too.

To reiterate from earlier.
On my older desktop with the 7600gt, it was a matter of nothing more than the fact that the video card wasn't getting enough power. I was using a coolmax 350w which is the minimum power requirement of at least the bfg 7600gt (i let the video card manual suggest what wattage i needed). Coolmax is perhaps not the best brand, but definitely way way better than cheapie paper weight psu's. I never burned out that old psu, i just shoved it in a computer that wasn't going to need to meet the power requirements of a 2006 gaming rig. I then upgraded to a coolmax 450w psu and had no more stability problems ever again.

Get a good psu definitely as others have said. But never only just meet the minimum power requirements for any video card. Otherwise you'll just have system stalls and daily random reboots which is what happened in my old desktop until the psu upgrade.

[Davros]

topace i had a similar problem, mboard died had a good agp which i wanted to use, but i hated spending money knowing that i would have to ditch the board when I upgraded my gfx card
the solution
asrock P4Dual-880Pro (agp and pci-e)
http://www.asrock.com/mb/overview.asp?Model=P4Dual-880Pro

[Klaustrophobia]

if you can do without the desktop for a while, maybe the best bet would be to save up until you can just do a new build altogether.