Problem began with noisy fan, then progressed to spontaneous shut down. I disconnected all external CABLES and opened COVER to clean. Hooked everything back up (except power source to disc drives...oops forgot those), and everything powered up. Got questions about primary and secondary slaves. Disconnected everything again and connected everything, including drives, but now computer will not power up at all. Does anyone have any suggestions as what to try next? Welcome!
We are going to need more info.
Which OS are you using?
What do you mean with doesn't power at all?
Like you can't get past the bios or it doesn't start at all?

Jonas Please forgive my computer ignorance! For OS I will say Windows, and by not powering up I mean not at all.

When I took everything apart I mean all the way down to the heat sink and I had no idea what thermal paste was so of COURSE it didn't get replaced. Could I have burned something up or shorted something out?

The computer came up yesterday and I made it to the CMOS and was totally confused. I'm sure I pressed all the wrong buttons and shortly thereafter the computer stopped responding. I then did a hard shutdown. Tried messing with it again by disconnecting and connecting everything again (including drives)and now nothing.ok so your saying your computer is not powering up at all..........hmmm well

The heat sink is the thermal compound that you put on your cpu ( computers brain under the system fan) and if its not applied correctly it will over head and cause a system shut down , now because im not there i cant see the damage its done or what has happened , i would say try and put a new layer of thermal compound on the cpu (If and when you decide to do this i will go through it with you step by step to avoid any issues ..... the other alternatives is to purchase a new psu , (power suply unit).......heres a picture of the thermal compound

http://www.maplin.co.uk/Module.aspx?ModuleNo=32417&C=Maplin&U=SearchTop&T=THERMAL%20HEATSINK%20COMPOUND&doy=25m7Are there any ways to test the psu? What would keep it from coming on? Could a short in the motherboard affect it?I don't want to rule out your motherboard has already shorted out ......... so it is possible , i don't think there is a test for your psu no , but there cheap enough to BUY you can get a 500wats for $40 or 30pounds ........ if you do decide to get a new psu ....... and it still doesnt work go back to the store and get a refund with that money and add a little extra get yourself a new motherboard ....


note Before doing the refund ..... check the stores return policy you may have to shop around a little , or you can find a CHEAPER 2nd hand one and just use that to test if it is your psu .


If your happy to open your computer ........ i will show you what has to connect from the psu to the motherboard......... everything circled in green is what is meant to be connected

Note: This is a shot of my mobo , your layout may be different...



Have a good look: Quote

The computer came up yesterday and I made it to the CMOS and was totally confused. I'm sure I pressed all the wrong buttons and shortly thereafter the computer stopped responding.