I think my 8-pin ATX 12v is failing

Suddenly I'm having the problem of my PC freezing at random times and i have to do a hard shutdown to recover. Sometimes, however, the PC will refuse to boot up after I force the shutdown. Fans and GPU led come on but i get no signal to monitor. I don't think it's the GPU causing this as when this happens the GPU led stays on and it usually turns off as soon as windows begins to boot as i keep it turned off(This tells me the PC is not booting at all because like I said the led would usually turn off about when the welcome screen comes up). The reason i believe the problem is with the motherboard is because I've found that unplugging and plugging back in the 8-pin 12v for the cpu temporarily remedies the problem. The PC will boot and I will not have any problems for a day or so. I've tried to look at event viewer to see if something is wrong from there but there is no record of anything going wrong at the time the PC freezes. I really would just like some help figuring out if it's the motherboard, the power supply, or something else entirely that's going wrong. Any help is greatly appreciated, Thanks in advance!

PSU: Rosewill Fortress 550w

CPU:FX-8350 @stock clocks

MOBO:Asrock 970 Extreme3

RAM: 8Gb DDR3 1333 G.Skill Ripjaws

GPU:Gigabyte GTX 970

SSD:OCZ Agility 3 

HDD:1 TB WD Black, 500 Gb WD Green

Something like this could be a number of things. It actually sounds like a possible problem with your power supply, I would pick up one of these cheap testers. Plug everything up, and let it run for a bit on the tester since the problem is intermittent. If any of the lights ever shut off, then there's a problem with it.

Next, you could try getting a hold of a BIOS speaker, which will hopefully give you a beep code for when you have the weird issues with booting up.

In the meantime, you could try running some tests on the RAM and CPU. I would let Prime95 run for some time to see if anything may be related to the CPU, and burn Memtest86 to a flash drive to test your memory.

I'll give these suggestions a go tomorrow but I can say that I do have a bios speaker hooked up but i never receive any beeps.

Remove that thing with the OCZ sticker. Chances are its that. Boot off a live linux usb to test system stability with it gone.

If you've previously played with overclocking the cpu perhaps there has been damage to the motherboard. As is does have it weaknesses when running such a demanding cpu.

One sure way to find whats wrong as with anything is swap out what parts you can until you find the culprit, but chances are (and my gut feeling) is that its that old ssd. 

As far as the OCZ "thing" goes, if it was that wouldn't I get a "No boot device found" message? Because I'm not, in fact i get no bios at all. No bios, no error screen, no error beeps.

Not exactly, the weird faults I've seen ocz drives give boggles the mind. Ask any service tech who has had to deal with em. 

Thanks deejeta I'll take that into consideration. I apologize for creating a zombie here, but I figured I would close this topic up. I went out and picked up a new motherboard (ASUS Sabertooth R2.0) and it has actually stopped happening. Before I went and bought it I did try re-installing windows 8.1 and also windows 7 but it still occurred on the old MOBO. Sorry it took so long but I wanted to make sure it wasn't a temporary fix. Thanks for all the input, I wish I could've done some more troubleshooting to pinpoint the exact cause however I've been really busy.