Computer won't boot

[FxCMYfOB]

I recently got a new heatsink installed in my computer, and now my computer wont boot. with my power supply on, i have a constant green LED light on my motherboard. When I hit the power button, my cpu fan, gpu, and case fans start for a split second and then everything just turns back off, except the constant green light on the mobo.

 

[thescreensavers]

Sounds like a mobo issue. Have you tried resetting CMOS(Bios) ?

You might of hit something when installing your new heatsink.

Does your PSU fully power on? Grab the 24 pin connector and a paper clip. Jump and Green wire with any black, then plug the PSU into the wall, if it powers on then it should be ok. ( No voltage is in the paper clip if you jump a green/black)

 

[FxCMYfOB]

trying to reset the cmos(bios) now, im not sure i understand what you mean in the second part.

 

[thescreensavers]

The second part is just to test to see if your power supply works

Does your PSU fully power on? Grab the 24 pin connector and a paper clip. Jump and Green wire with any black, then plug the PSU into the wall, if it powers on then it should be ok. ( No voltage is in the paper clip if you jump a green/black)

The 24 pin connector is the big power cable that plugs into your motherboard

Get a paper clip, open it up. Stick one end into a Green( The color of cable that is attached to the hole) and any black one.

Then plug in your Power supply into the wall, it should turn on and stay on. If it turns on then turns off like you saying then there might be your problem.

 

[FxCMYfOB]

oh okay thanks that makes a whole lot more sense. thanks for all the help. this computer has been down for something before the heatsink because pressing the power button simply wouldnt turn the computer on. today i managed to fix that problem which was most likely a wiring issue, but now after the install it's not working again, i'd like to slowly add parts to this computer and eventually flush out all the old parts.

 

[FxCMYfOB]

ok so i tried what you said with the paper clip and it is staying on. any help now?

 

[thescreensavers]

Ok so its most likely not the PSU. I had a very similar issue the fans and power would kick in and it would turn off, then sometimes it would turn on but no boot. After like 30 tries it booted. The mobo was the culprit.

If you have reset the CMOS and still a no go you can try reseating the ram, try one stick of ram alone..ect, GPU..ect check connections..

if all is connected right..ect then its most likely the motherboard that crapped out.

 

[FxCMYfOB]

thanks a lot for the help. you're a livesaver. i hope i can get this working before i go to sleep

 

[Devilpapaya]

I'd go down to a minimal build; 1 stick of RAM, HDD, PSU, and GPU (unless you have onboard graphics that works, then leave off the GPU) and see if it works, if it does then add pieces one by one til it stops working. If the minimal build doesn't work, I agree with screensavers, sounds like a MoBo issue.

Also, this may sound dumb as hell, but make sure the power button isn't getting stuck. I troubleshot a computer for about 2 hours with a similar problem before I realized the power button (not the acutal plastic button, that popped back out correctly, but the piece inside it that actually makes the connection) was staying depressed and causing it to hard-shutdown moments after powering up.