I'm stumped: system freezes, requires hard reset

[Rhykker]

Hey folks,

I'm completely stumped and would love to get some top minds on this.

Here's my situation and what I've tried to do to fix things...

Thursday night:
- Computer working perfectly. Turned off computer, plugged in new SSD for storage.
- Turned on computer; DOS error screen telling me there is no bootable drive inserted. Looking in the BIOS, my old SSD with Win7 is not being recognized anymore.
- I unplug the new SSD, reverting the hardware setup to its previous, functional state. Same error.
- After much futzing about to no avail, I change my old SSD's SATA cable and plug it into a different SATA port. Windows boots up, computer works.
- Several hours later, I play a game (Heroes of the Storm) for a couple of hours, and get a hard freeze. Sound is gone, everything on screen completely frozen and unresponsive. Requires hard reset.
- After hard reset, freezes continue to happen every ~10 minutes, without even running games or anything intensive.
- Start frantically trying to update drivers between freezes. Successfully update BIOS and some system drivers, but then start getting errors about GeForce.
- After doing all the driver stuff and futzing with some BIOS settings, freezes stopped. Coincidence? I don't know.
- Everything functional for next couple days...

Sunday night:
- Experienced no issues Friday night, despite ~4 hours of running a game (Diablo 3).
- Saturday, plugged new SSD back in. Everything works fine.
- Everything was fine until Sunday night. After a few hours of Heroes of the Storm (same initial trigger game), hard freeze.
- Ran check disk; fine.
- Uninstalled and reinstalled graphics drivers.
- No system restore point exists before these issues began.
- Freezes not occurring as frequently as on Thursday night and situation seems to be resolving itself faster (it has not frozen at all as I have been typing this up).

What's going on here? Is my graphics card overheating? But then why didn't the long Diablo play session trigger it? Why did inserting the new SSD trigger this whole situation?

And most importantly... how can I fix this? 🙁


System specs:

Win7
GTX 760
ASRock Z97 Pro3
16GM RAM
Kingston SSD (with OS)
i7-4790k (stock clocking)
Western Digital HDD (storage, no OS)
New Crucial SSD (storage, no OS)
PSU is 500W

 

[Rhykker]

Just froze again right now; wasn't doing anything specific, just light web browsing.

 

[Rhykker]

Update: I ran three memtest cycles, came up clean - I know I should run for at least 7-8, but I didn't think it was the memory anyway. I remembered that this all started when I plugged in a new SATA device, so I futzed with the SATA cables some - I thought maybe the SATA for the SSD wasn't connected properly - and it didn't freeze again. Going on about 12 hours of use without freezing, now. Not out of the woods yet - would like to see several days, maybe a week without freezing before I feel safe, but so far... promising.