PC won't power on, just fans

[misajay]

Recently, my computer began to power itself down randomly. Just today, I was playing a game and it powered down, but this time the fans came back on but nothing else. No boot, no led indicators, just fans.

I was already suspecting that the cause was my power supply. I had checked all connections, cleaned out dust, many times. Is this most likely what is failing?

Some notes about my build:

Windows 8.1
Motherboard: Asus P8H77-I
PSU: Silverstone ST50F-P 500W
CPU: Intel Core i3-3225
GPU: Radeon HD 7950
HDD: WD Red x4 (3TB), WD Blue x1 (1TB)

My computer runs 24x7 as I use it as a server / htpc / gaming rig. I have calculated my recommended usage many times and I always come in around 350-400W recommended. Did I somehow overuse or misuse the PSU?

One final note, the PC began to random reboot a few days after I opened the PC case to clean out dust. I didn't disconnect anything so I feel like this is more coincidence. Could it be related?

Thanks for any help!!

 

[uplink-svk]

Ow, You should've started to solve this issue when it started happening :\. Well, anyway. Please disconnect everything from Your computer, and leave only motherboard connected to PSU and one ram module [cooler on cpu ]. And try to turn it on. Don't forget to put out Your graphics card and disconnect it from PSU. The same goes for HDDs, by HDDs. And tell me if it works.

 

[misajay]

Thank you uplink-svk, your post gave me an idea. I pulled out the power supply (everything still attached), plugged in and turned on to make sure what was being powered and what was not. So, with the PSU hanging out half way I powered on and everything was fine. Everything booted, all lights were good.

So then I thought there had to be a loose connection. I wiggled each individual cable from the PSU, nothing. I wiggled the PSU cable to the motherboard near the motherboard and it shut off (like it had been). I unplugged, double checked to make sure it was plugged in all the way and it was. I powered on, wiggled again and it turned off.

So I have replaced the cable from the PSU to the motherboard and everything is working at the moment. I have wiggled and it seems stable. I believe it may have been a short in the cable somewhere...?

I will keep updated if there are any other issues!

 

[uplink-svk]

misajay - short or damaged, and thus not pouring enough juice to the system, which could cause short outage, thus, system shut down.