Faulty Motherboard? 'No Signal' on known good GPU/Monitor

I have an AsRock 970DE3/U3S3 that I bought for my first build a few years ago (11/2012) and recently upgraded the GPU from an HD7770 to a GTX 770 (May '14).

The other day (more like a week ago) I went to turn it on and was greeted with 'No Signal' on the monitor. I checked the connections, swapped the cables, swapped monitors, still no dice. At first I thought it was the GPU but I borrowed a friend's test bench and it works perfectly. I put in my old 7770 and the problem persists.

Today I decided to try it out again and everything seems to work. Booted into Windows 7 and I figured it was just the Gods playing with me. After a few minutes, though, the screen goes blank and shows 'No Signal' yet again.

What could cause this and how could I check it and/or fix it? 

put back in the GTX770, and clear the cmos of the mobo.

ofc dont forget to set date and time again after resetting the bios.

How would I clear it? IIRC, it has a jumper but I don't have the manual.

*Edit*

Put the jumper on, started, nothing. Switched the jumper back, started, nothing. Pulled battery too. Nothing.

hmm if you gpu´s work fine on the test bench, then i have a bad feeling about the mobo.

The Asrock 970 boards aren´t the most reliable board arround, to be honnest.

What's a good one to replace? I don't want to keep replacing it.

idk which cpu you have, but something like Asus M5A97 R2.0 would be good.

But first test your gpu´s on the test bench.

GPU runs perfectly. Loaded up BF4, maxed it out, no problems.

I run a Phenom II x4 965 Deneb but I also have 2x4GB 2133MHz G.Skill ARES so I'll need something that's AM3+ and supports 2133+MHz.

Asus M5A97 R2.0 should be fine. or the EVO.

Or Msi 970A Gaming.

2133mhz ram, i dont think that a phenom cpu will support that ram speed. But if you want to run 2133mhz you need to set the timings etc in the bios by hand anyway. But with the phenom you probably need to OC, because the Phenom cpu´s only have a 1333mhz mem controler.

I've not had a problem with it before. It's been this way about a year.

offcourse the ram wil work thats not a problem. but you need to set them to 2133mhz by hand.

otherwise they will run on 1333mhz. the only question will be how high the phenoms can go with ram speeds, without Northbridge overclocking.

I think I'll be alright with them, even at 1333. I originally bought them for a Kaveri APU (8750K) setup that I ended up selling to a friend and kept them.

I'm looking to spend right around $100 on the new MB (sans shipping). What would you recommend? 

United states?

http://www.newegg.com/Product/Product.aspx?Item=N82E16813130790

6+2 powerphase digi vrm. good board. with alc1150 audio chip and killer lan.

Did you also tried your psu on the testbench by the way?

Yes. Tried everything on the bench that would fit. RAM is good, PSU is good, GPU is good. Only things not tested were MOBO and CPU.

Thanks for the information, mate.