Post issues, graphic issues

[Huey]

So a couple days ago, my PC just started crashing heaps out of nowhere, usually this is because of dust so I opened it up cleaned it and all that. Went to plug everything back in and I get 'No Signal Detected' when using HDMI and I have tried VGA get the same thing. So I am using my on board graphics thing in my CPU just so I can use my computer at all. But I fixed me crashing just by cleaning, but now I have the issue with the display. Also occasionally my screen will go a bunch of different colours then just turn off and I am just lost with that. After that first time it happened I couldn't even get it to post but I just came back 10 minutes later and it worked. Overall so much shit is happening and I am just so lost with everything and not sure where to start really. I have had my PC for a good 3 years now with everyday use so I feel like something is bound to be wrong hardware wise. Posted my specs below.

 

Processor

Intel(R) Core(TM) i5-4670 CPU @ 3.40GHz

Video Card

EVGA Geforce GTX 980 SC ACX 2.0

Motherboard

Gigabyte B85M - D3H

RAM

G.Skill Ripjaws X 8gb