I opened my case today to clean out some dust from inside my computer. After finishing cleaning it out I turned the computer on before putting the side to the case back on. As I was putting the side of the case on the computer suddenly shuts off and starts back up within a couple seconds. I continue to put the side on but again the computer shuts off and starts back up. This time I turn the computer off my self and secure the side of case on. I now go to turn the computer back on except, nothing happens now. I check to make sure everything is plugged in, but still nothing happens when the power button is pressed except sometimes a light on my videocard will turn on for almost a second and then go out. What could be the problem?

I have a Gigabyte P35-DS3L, core 2 duo e4400, hd 2900xt, ocz platinum revision 2 (2Gb) memory, and Abs Tagan ITZ series 700w.

Thanks

Wait, let me get this straight - You had the pc on while you open'd it and cleaned it?

If so, im not surprised if you havent killed anything from static etc.

remove your psu and all the wires, put the power chord back into the psu and get a clip or a piece of metal wire and bend it into a U shape, and stick one end in the green wire slot of the 20+4 pin plug and any of the blacks, and hook up one of the molex wires to like a casefan or something. then press the power button, if it doesnt do anything then the PSU is dead, but if the fan spins, then the psu isnt dead and you've probably shorted something...

hrm.. well it worked before you cleaned it, which suggests to me that you have knocked something when cleaning it. Just check silly things such as all the power connecters, hard drive is propperly connected, maybe try and reset the CMOS and like dudbomb said, just check the PSU.

Roblob cleaned the system while off.
It sounds like a short to me. Maybe some metallic dust rested where it shouldn't be, but it could have been static damage.

My suggestion would be to:
1 can air the thing well, even behind mobo (again to get rid of anything shorting out the motherboard).

2.) Check for lose cables/wires/plugs/ and screws!

DO NOT bother to reset CMOS, its not the issue at hand and will cause some extra work.

If you still cant turn on, unplug the power to:
CDROM
Hard drive

Disconnect all peripherals (i.e. USB devices)

and if still no luck, remove video card and other PCI cards
-----------------

Remember to be very careful and ALWAYs ground yourself.

If you used a feather duster or similar, you made static and now your screwed.

If you vaccumed you may have sucked up a jumper.

dudbomb, the computer wasn't on while I was dusting. thanks for the help I'll try those things and tell you how it goes

I started the power supply fine the way dudbomb explained, so it's something else

so I put the psu back in now and tried to start it now with cdrom and hard drives unplugged, unplugged all peripherals, took out all pci cards and my video card. Basically all that happened is the fan moved a tiny bit and then it stopped. what do I do now?

The fact that the fans spin up under these conditions does not indicate much. First, there's a minimal load on the PSU. Second, the PSU could have internal faults that could prevent the PC from booting even if all the supply voltages are present.

Doublecheck all the cabling ang connectors. For more troubleshooting suggestions:
http://www.tomswiki.com/page/Troub [...] +New+Build