5.5 year old desktop PC won't power up

[Ethanethane]

Hi there,

I have a 5 1/2 year old PC that's been working fine since I built it with the help of a friend (first time). A few months ago, I noticed some performance issues for the first time - processor intensive games would slow down, programs took longer to boot. Long story short I realized that the stock cooling system was beginning to fail. AMD Overdrive told me my GPU was running up to 20 degrees outside its thermal margin at high load. So I decided to buy a new case fan (I know, probably not enough to fix the problem but I figured I could start small and work my way up) - a Noctua 120mm that had solid reviews on Newegg and Amazon.

I did more research, opened up the case and realized the cooling system had been configured wrong all these years. All my fans were blowing out the vents, and nothing was supporting intake or blowing directly onto the cpu/heat sink. So I decided to reinstall all the fans. Put the Noctua in as rear exhaust plugged into the mobo as fan1, installed one of the stock Cooler Master fans as side intake and plugged it directly into the PSU, and the second stock as bottom intake plugged into the mobo as fan2. Plugged in the computer, pressed power, and nothing happened. No whirs, no fans, no boot sounds. The indicator light on the mobo is steady green. I checked and rechecked all the jumpers and cables, especially the mechanical power button's connection. Today I removed and reapplied thermal paste to the cpu heat sink, but that didn't work.

It's very possible that I discharged some static while installing the fans - did I fry my motherboard? Did the new case fan overload the PSU? Is this what happens when your CPU has been running too hot for as long as mine has? I haven't checked to see if the PSU is faulty - a 550v Corsair that's only 5.5 years old - because the motherboard seems to be getting power. I don't know what else to do. If anyone has thoughts please share.

ASUS M4A79XTD EVO
AMD Phenom II x3
Windows 7 Home

Happy to provide any additional specs or context. Thanks so much for your time....and if it comes to it, I may be asking advice from you all on my next build... 😕

[patio]

A few things i would do 1st...
Try running it without the GPU...any difference ? ?
If no...borrow a known good PSU and swap it in there...you'll know overnite...

If it does manage to boot properly i would run diagnostics on the HDD from the HDD manuf. site...
I'd also run MemTest for the RAM...let it run min. 1 hour.

Best of Luck and let us know...

[Ethanethane]

I tried removing the graphics card, no change. Though I'm not sure if my mobo has a built in card (I don't think so). I don't have an extra PSU, but if it was faulty would the indicator light still glow green? I'm a little wary of buying a new one since I feel like it's the one component I may NOT have to replace if I have to rebuild the rest of my computer.

Thank you for your help though. If I do get the thing running again I will perform those tests.

[Geek-9pm]

This link explains the PST and BEEP codes
http://www.computerhope.com/beep.htm
The fact that it can do a beep code indicates that the CPU did start up and did some kind of test. No beeps  means it did not do the POST.
If there is not video device, there will be a beep code.

The computer power-on self-test (POST) tests the computer to make sure it meets the necessary system requirements and that all hardware is working properly before starting the remainder of the boot process. If the computer passes the POST, the computer gives a single beep

[Ethanethane]

No beeps (or any sounds for that matter). It's as if the power button is not plugged into the motherboard (though it is).

Thank you for the link - very interesting information.

[patio]

I never suggested buying a new PSU...thats why i suggested borrowing...
A green MBoard LED which is minimal draw is no indication of if the PSU is good...

I'm not sure what you mean the MBoard does or does not have graphics...look at the back of the case to see...or post the info here...