I addressed this problem in a few threads but I now seem to know a little more so here goes. My new (1month old)PC will not start up properly anymore. This is the whole story;
Won a geforce 7900GT so wanted a new PC to make use of it, realised I needed a new PSU to take ot so bought a thermaltake 420W PSU and put it in-all was fine. Added an second gb of Ram and then the card...and still all was fine. About two weeks ago the PC froze while running some diagnostice/antivirus etc. and I had to turn it off. Now when I turn on the power switch on the wall the PC starts up but the power LED does not come on and the screen remains blank; the PC always needed the power button on the case to be pressed before.
I can turn the mains switch off/on and eventually coax the PC on and it runs fine after that for hours; can even be restarted but from a cold start I have the same problem. Rang ACER today and they will look at it but say my warranty may be void because of the GPU and extra RAM which may have caused the problem even though I was told this upgrade was allowable. So I am reluctant to send it away. I put the old PSU in today (so my warranty would not be totally void when they open the case) and same problem and then I slowly took out parts, reseated etc.
When I took the Graphics card out and used the onbard graphics the Power LED comes on and it seems to boot OK now...BUT it still comes on when you turn on the mains rather than pressing the power button.
So, I think the PSU is OK although neither of them may be powerful enough for the machine (I really hope it is this as I can get a bigger PSU).
But I may completely lose any free repair if ACER get a bit picky and also get charged. Any suggestions guys...I really don't want to send this PC away as I am using it for a contract at the moment but something is obviously amiss and I don't want to waste a perfectly good GPU.

Ok, always one to experiment, I tried turning the PC off by pressing the power button and then I cleared the CMOS. Not sure which one did the trick but it all works as before now so I put everything in as was yesterday i.e. GPU, RAM, Thermal take PSU etc. and so far (fingers crossed) it seems fine.
Still, I will post any change to this.

Bugger...started again. Just turned it on after a few hours switched off and power LED did not light...fans whirring away but nothing on screen and no system beep.

i also got have that problem right now.. and I can't figure it out.. why is that happen and how to fix that bugg.

wirespy99

you could try backing up your files then doing a whole computer clean of the hard drive.

I had the same problem as you in the past. I had a repairman come over and he didn't see anything wrong, so he reseated everything to see if that would fix it and it did.

Try re-seating everything. I don't know much about computers so I don't know if re-seating "everything" would be safe, but re-seat everything you can and that might solve the problem.

thanks:

louis15
splinters
sockrocker

perhaps i should try that..
aregato gusai mas

wirespy99