Having some issues with my PC

Hey everyone, I'm running into a bit of a headache with my PC. Basically, it just froze right in the middle of what I was doing, so I had to force a shutdown using the power button. When I tried to boot it back up, nothing happened—the power light came on and all the fans were spinning, plus the hard drive seemed active, but there were no beeps and absolutely no picture on the monitor. So, the next day, I decided to pull out both RAM sticks to see if that helped. The PC actually beeped three times when I did that! Once I popped one stick of RAM back in, it booted up perfectly fine. But when I tried adding the second stick again, I was right back to square one—nothing. For now, I've just been running it with that single stick. Fast forward to today: I put that same single stick back in, everything started up normally, but then—right in the middle of a gaming session—it crashed hard. I got that "Your PC ran into a problem" error from Windows, and it just stayed there. So, yeah, I'm back to only being able to use one stick of RAM. I'm trying to figure out exactly which part died, and I'm also curious about these voltage readings—why are the fluctuations so massive? Here’s my current setup: MSI 870-C45, Intel Core i7, two 4GB Apacer 1333 MHz sticks, GeForce GTX 1gb, an 840 EVO SSD, a Seagate 120 gb, a 1 TB HDD, and a Samsung OCZ 500w http://imageshack.com/a/img537/1627/rv9yB9.jpg

http://imageshack.com/a/img537/1627/rv9yB9.jpg

It looks like the RAM is acting up...

That’s pretty much it, there isn't really any complex theory involved; I suppose you just download MemTest86 and run a scan on your RAM, and if it starts throwing errors during the process, then you know the memory is likely faulty and that's all there is to it.

That looks solid for the RAM—but man, why is there such a huge gap in the voltage?

What voltage are we looking at here?

Honestly, I don't think you're actually facing any voltage issues at all...

I can't recall the exact number off the top of my head—but if you check the link, there's a screenshot from HWMonitor. Under the +12V section, it shows something like 4 point something. Is that actually okay?
Also, I should probably mention that the RAM currently in the machine only seems to work when it's in that one specific slot—it won't boot in any of the others...

I suppose you might want to go ahead and run a scan on the RAM anyway.

I’m just a little worried about what happens if my PC won't boot once I pop that extra stick of RAM in.

Well, you mentioned before that you managed to get it to boot once even with those faulty memory sticks. If you run into the exact same issue again, I guess it might be a good idea to run MemTest just to be sure.