Fairly recently, my PC has started experiencing freezes. At first, I was convinced it was google chrome. My PC would lock up entirely (with no errors or blue screens, nothing like that) while I was using google chrome, often while zooming or closing a tab. I'd be forced to restart at that point. I swapped to firefox two days ago.
Discovery has also experienced issues, resulting in issues alt tabbing (Instead of a quick swap, it'd take a full 10 seconds of staying on a black screen before switching to my desktop), and also removing my mouse from my screen. I could still see it ingame, and it still technically existed on my desktop, but it was invisible. I tried swapping my resolution size at that point, seeing if it'd fix it. My screen turned black, and my PC froze, eventually giving a NO SIGNAL on my screen. (Note, the framerate was fine ingame, and my mouse didn't recover after closing FL)
At times, games like Warframe, Planetside 2, or even Warcraft 3 would experience severe framerate drops. As an example, I could sit on the login screen for Warframe, and generally average 140-200 frames per second. But when my computer is acting up, I'll get, at best, 20 FPS. It does not fix upon restarting the game, and I have to reboot for the issue to resolve. Alt tabbing, again, is affected, going slowly (but my mouse remains on screen this time.)
I have yet to experience the full on freezes the last two days after swapping to firefox, but I have had several, 2-5 seconds freezes.
Memory checks have given me no problems. A hard drive check has told me nothing. I've dusted, made sure everything is firmly plugged in, defragmented, everything. I've updated windows, Java, Flash, video card drivers. I've scanned for viruses, cleaned up my PC, scanned for malware.
My PC barely goes over 50, maybe 55c while playing intense games. I've had no artifacting, and generally, games work just fine, save for the alt tabbing and framerate issues that're sparse throughout the day.