Well, the old saying in IT is
"no pain-no gain!". How bad do you want your problem resolved?
Based on your post above, you spent more than 5 min. troubleshooting it so far. I'm not the fastest guy in the world, however, I've solved problems during my 45 years in computers that were deemed unsolvable by my bosses, my teachers, and my co-workers for some of the biggest companies in the world. Not tooting my own horn, but this has been well documented in my industry. That being said, not everyone is willing to go through the work necessary it often takes to solve tough problems. I always encourage my students and even my competitors to go the extra mile and any problems can then be resolved.
You haven't opted my GPU card swap-out, and that's ok, but that would go a long way to narrowing down your problem. Also, you mentioned you had a 600W PSU but not the Make/Model.
Is it at least Gold-Certified Plus? If not, you could have power problems. Many users here with flaky problems such as BSODs, Black Screens (such as yours), freezes, crashes, hangs, etc. often find out that if they scrimped on the PSU when building their PC, down the road many if not all of these problems can be attributed to poor power-supply problems. In self-built PCs, no component is
MORE important in your PC than the PSU; not the Mobo, the CPU chip, or even the GPU card or RAM. Poor quality power can cause a plethora of problems in PCs, as it's the common-thread component that conducts electricity to every single component in your PC, even your fans. There are many articles and books on just this subject if you're interested, post back for links.
At this point, I'd agree with you that you are having multiple problems that appear to be hardware based. You might consider re-speccing your components and make sure you have a high-quality PSU that can handle all of your
EXISTING components. Many users upgrade components such as storage (adding multiple hard drives), multiple GPU cards, etc. but forget to upgrade their PSUs. There are volumes written about this if you sniff around the PC building industry a bit. Post back your PSU specs, and we can give you a quick
"Go-or-no-Go" on what you are using. If we don't like what you have or haven't heard of the brand, we'll recommend you replace it with a name brand high-quality. Top-end PSUs run from about $120-$400 US or more. Once we get to the bottom of the PSU question, we can turn to your Mobo and other components and try to figure out if 1 or more of them has failed.
This is quite likely as you said in the beginning of your post that your computer was running normally until recently.
Get back to us and we'll advise you further.
Best,
<<<BBJ>>>