Computer crashing/trouble booting

dango

So i'm trying to figure out what's going on with my computer. I built it about 3 years ago and haven't had any problems at all until a short while ago. I haven't added or changing any hardware lately.
The computer sometimes crashes about 1 minute after I log in to windows. The screen just freezes until i restart. This can happen a few times in a row and then it will run for hours without a problem.
Today when I tried turning it on, it started up and I could hear the whirr of the fan starting up and then it just shut down altogether. There is no mobo noise to indicate a problem.
I'm not sure how to troubleshoot the problem if the computer won't start up. Could it be a loose connection or the psu acting up or something else?
Any advice would be appreciated.

A short video of it:
https://drive.google.com/file/d/0BxOIluEVK_pvT2RmRHp6b09sOVk

Intel Core i5-2500K Box, LGA1155
MSI P67A-C43 (B3), Intel P67, ATX, DDR3
4GB-Kit DDR3 Crucial Value PC1333 CL9
Samsung SpinPoint F3 1000GB, SATA II (HD103SJ)
Super-Flower Amazon 80Plus 550W
Xigmatek Asgard III Midi Tower - black, ohne Netzteil
SAPPHIRE TECHNOLOGY Radeon HD 5850

Open the case and check for the dust bunny. Heat is the enemy of computer

Potatoeman

Did you open it up and look. My liquid cooling system was overheating and it turned out to be dust blocking the fan vent. If you dont see anything obvious look for fans stopping but it sounds like the video card may have an issue.

dango

I noticed there was some dust inside particularly around the fans but didn't think it could cause such problems?
I unplugged the two pci connectors from the gpu and it still failed to start up so I think that rules the gpu out.

Curry Addict

first step is to hoover it out imho. all fans and anywhere dust can accumulate. particular focus on cpu fan and heatsink. Then reseat all connections, will sort it 90% of the time.

dango

I'll get some compressed air and thermal paste and see what I can do.

dango

So over the last couple of days I managed to get my hands on some compressed air. I gave the fans of the CPU and memory card a good clean and the case in general but the problem is persisting. The computer fans start but then shut off after about 3-4 seconds. I'm pretty stumped about this.

Joeface

Any chance its is a blown capacitor , Should stand out when you look at the board , Bulged on the top of one of them.
This was a fairly common fault years ago , Don't think it would be an issue on the newer boards but worth a look

dango

So i've resolved the issue. I took apart the cpu and GPU heatsinks, gave them a further clean and replaced the old thermal paste.
Thanks for the suggestions!