Power Cut causing power issues with my PC/PSU

Yesterday, as of writing this post, all the power to our household decided to cut itself due to our garage power being faulty, however that's unrelated. Of course this included cutting the power to my PC. After we had regained power, I switched on my PC and everything worked as normal, all the fans, LEDs, displays etc. Nothing out of the ordinary.
Move ahead about 2 hours, and everything is still working perfectly. Then, I decide to switch on my webcam, which caused some kind of fault with some of the usb power. I have several devices plugged in via the rear I/O usb. (Mouse, keyboard, microphone, xbox controller, headphones, keyboard (the musical kind), and my webcam). After opening the webcam software, half of my usb devices suddenly turn off and become entirely unresponsive. (I could mainly tell because of the leds, things such as my mouse, keyboard, xbox controller, and the webcam itself) I remember my microphone and headset remained powered. Nothing other than that happened, no graphical issues, or other visual clues. I plugged in a spare, wireless mouse into the usb ports on my case and used that to save what I was working on and safely restart the PC via the software. After this restart, everything returned to it's normal state as if nothing else had happened.
After I had finished on my pc for the day, I left it in sleep mode until the next day.
When I got home from school today, I pushed the power button as I usually would to wake the pc up. However this time it didn't load up any software. There was a blank black screen, and I had free control over a cursor. The pointer arrow had a small disk next to it. Again, I rebooted my pc, this time using the reset button on my case. As before, the restart booted up the pc as normal and I could use it again like nothing had happened, until a few hours later where all the same usb devices that turned off yesterday turned off again, leaving only a few on. This time I just rebooted the pc using the reset button on the case. Again, the pc rebooted as normal and I carried on with my buisness. A few hours later I put my pc to sleep again since I had to go out for about 3 hours. When I returned and woke up my pc, the same happened as earlier, blank screen with a cursor that has a small disk next to it. I restarted my pc, and it worked fine.
I was getting curious, so I put it to sleep, and immediately woke it back up. This time it woke up normally returning to windows and all my applications were still open. And then, here we are now.

What I think is happening: Due to the fact that all of this has only happened after the power was cut. It must have been caused by that primarily. I believe the actual fault to be the PSU, and there is some kind of issue with the power to the usb ports, as well as the ram sockets during sleep. I think that because that would be the only logical thing to me that would cause failure upon waking up my pc after a longer period of time. While only leaving it asleep for a shorter period of time causes no apparent problems at all.

Hopefully someone can help me with this by telling what is causing the problem, and if there are any ways I can go about fixing it.

My PC Specs