Really strange behavior

So for the past month, my PC has been acting up. Firstly it would freeze during high-stress gaming, and then at just (seemingly) random times. I cleaned out the CPU with the thought that it was overheating. It seemed to work more or less, but would start this behavior again every once in a while.

In the last month, during these behaviors, my monitor would black out randomly for a few seconds. Then once it went off completely for several minutes until I tried unplugging/replugging in the hdmi cable and that seemed to work.

Fast-forward to today, my PC has been acting even more strangely. I recently came back from Portland (had to ship my computer there and back) and when I finished hooking everything up, and turning on the computer the monitor kept saying "No signal" then going into power-save mode. I had tried replugging the hdmi cable, even removed and replaced the graphics card, and cleaned everything out again. I ended up having to restart the computer multiple times for the screen to finally show up. Once it did everything worked perfectly, I was able to run games with maximum settings with no lag or issues whatsoever.

Later in the day I put my comp into 'sleep' mode since I was going somewhere. Came back and pressed the power button and turned on the monitor, only for it to give me the "no signal" message again. I tried restarting my comp (usually have to hold down the button for it to shut down) but it kept shutting down automatically with a single press. I didn't get it to come back on until after restarting the comp several times again. Once it was back on, same as before... working perfectly.

Then just now, being stupid I put it in sleep mode again and tried turning it back on just to see, and same crap happened... only this time I'd restart the comp, it'd begin to register then go black, then come back and even put me on my desktop even though I hadn't put the password in... then the whole comp froze and I had to restart again and it started a disk check. I finally got it on now and like before it's acting like there's no issue. I'm afraid to shut it down or put it into sleep mode, as I may not be able to get it back again.

So I am at a loss. Earlier this month I ran multiple malware searches using the read and run me thing on this site, and it found absolutely nothing. So I'm just confused as to what the issue is. Is it the monitor, the cable, the graphics card, malware? I just have no clue.

Thanks if you've read through all that mess, and thanks if you can offer any help whatsoever!

 

Problem solved. Crappy graphics card is crappy.