Computer locks up completely, fans keep spinning. HELP!!!!

[notmegatron]

First of all, here are my specs.
AMD FX-8320 Eight Core Processor
MSI 760GM-P34
Mushkin Eco2 8GB (4x2)
Arctic Freezer 7 pro
EVGA 650GS (650W)
AMD Radeon R9 380

So here's my problem:
Since I built the PC, I've been having problems with it crashing during gaming. Some games run fine, while others will crash at relatively consistent intervals. The computer will just lock up completely. Sounds will stop, the screen and cursor will be completely frozen. The only way to get the PC back is by holding down the power button/switching PSU and restarting. Sometimes, it will be a BSOD, and the error message will be different every time. What's interesting is that some games will run fine for a while, say, 30-60 minutes until crashing, and then upon reboot they'll crash much faster, 1-5 minutes after starting.
Nothing obvious shows up in event viewer,
Here's a list of a couple games that consistently cause the crashes:
Divinity: Original Sin (30min, then 1-5min after initial crash)
7 Days to Die (~15-30min)
Subterrain (30-60min)
Red Faction Guerilla(30min)
Slime Rancher(20min)
MGR: Revengeance(~45min)
Prey (~15min)
Rome: Total War(+60min, but it crashes eventually)
PUBG(20min)
Fortnite(20min)
The Forest(20min)
These are pretty rough estimates. For contrast, here are some games that run indefinitely
RimWorld
Alien: Isolation
Skyrim
Dishonored
Dead Space
Outlast
Minecraft
Titanfall 2

Changing the graphics settings and resolution makes no noticeable difference, if there is one it is a small difference. There seems to be a correlation between the "stressfulness" of the games and the frequency of the crashes, but the outliers make it confusing. Dead Space will run fine on all the highest graphics settings, but Red Faction will cause the crashes. Rimworld causes no crashes, but Subterrain, a pretty simple top-down game, doesn't make the cut. Games also seem to crash much more regularly in customization menus. Absolver usually crashes while I'm changing my movesets, and XCOM 2 will crash while I'm setting up loadouts before a mission.
In addition, streaming will wreck my performance. Games that run fine normally will crash in minutes if I'm trying to share my screen.

Nothing is overclocked, and I often use MSI afterburner to raise my fan speeds, and it doesn't seem to have any effect.
Things I've tried:
Clean install of Windows 10
Updating drivers
Checking event logs, nothing obvious

Please help me.

 

[Jwpanz]

I could be a memory issue. System lockups are usually a sign of that. Conduct a memory test in Windows. Search for "Memory Diagnostic" in the Windows search bar on the tool bar. Follow the prompts and let Windows restart and run the test. Let us know what happens.

 

[notmegatron]

I could be a memory issue. System lockups are usually a sign of that. Conduct a memory test in Windows. Search for "Memory Diagnostic" in the Windows search bar on the tool bar. Follow the prompts and let Windows restart and run the test. Let us know what happens.

"The Windows Memory Diagnostic tested the computer's memory and detected no errors"

Oh, and I checked the PSU with a multimeter and all the voltages seemed normal, but I'm still unsure.

 

[Jwpanz]

Try adjusting the clock speed and timing of the RAM in the BIOS. It may run at an unstable rate wile gaming which is why you get those system lockups

 

[notmegatron]

Try adjusting the clock speed and timing of the RAM in the BIOS. It may run at an unstable rate wile gaming which is why you get those system lockups

I didn't want to speak too soon but it's been working like a charm since then. Some other issues have still persisted (computer will fail to boot occasionally, sometimes fail altogether) which again seem more like the psu, but the random crashing is what's vexed me for so long. Thank you! I'm glad it was such a simple fix.