First, I would like to start off by saying that this is not a Windows 8 exclusive problem, I've had it in Windows 7 and upon install to Windows 8, it still occurs, which is leading me to the conclusion that this is a hardware problem.
Ever since I built my machine in early 2014, it seems like it randomly freezes, there doesn't seem to be any root cause behind the freezing. During the freezing, it's 'responsive' but anything that requires disk access does not work, the drive indicator light on my case stays solid. I've also noticed especially lately, that when I play GTA San Andreas (a multiplayer extension) that my game tends to randomly freeze and if I unplug a USB and plug it back in, it usually unfreezes, if not, when I hit the power button, it instantly unfreezes (this freeze actually locks everything up, not just the disk); when playing BF3, it doesn't happen, but GTA SA is a pretty old game.
Also, on occasion, when shutting down my computer (sometimes abruptly due to above problems), the HDD isn't always detected, in that case if I unplug and re-plugin the SATA wire, it usually fixes it.
I run what I feel is a pretty typical setup, a FX-6300, a MSI 970a-G46 motherboard, 8GB of G.SKILL Ripjaw's, and a HD 6870 as a GPU. I've tried changing my drive controller mode from IDE to AHCI, which did seem to help with decreasing the frequency of the freezing, but it still occurs.
I'll list some things I've done as troubleshooting:
-Replaced my old HDD with a new WD Black
-Replaced my SATA wires
-Disconnected all other drives from my PC including my DVD drive
-Reinstalled OS from 7 to 8 (as mentinoed above)
-Ran Memtest86 which turned no errors
-Changed my GPU from a 4350 HD to a 6870 HD (wasn't a troubleshooting step specifically, just happened to do it)
-Reset my BIOS on a number of occasions
The obvious problem right now is that there are some serious issues with my motherboards SATA controller, and I already have a RMA ready with MSI, but I would like to hear any other input, as I'm quite frankly not even sure that MSI's synthetic testing is going to pick up on my issues at all.