system is running alright with some weird issues, but fsck says all superblocks are corrupt

first off, this is a longer story, and I am not very knowledgeable in any of this. So feel free to ask questions and bombard me with commands to try.

Last year in November I bought a new PC with a proper graphics card and after years of running Debian stable, decided to try something new and installed Kubuntu 19.10. I fell in love with everything at once – I mean no system is absolutely perfect, but I can even run World of Warcraft with acceptably rare crashes (wine, I'm sure) and the whole setup just feels good to me. So that's that.

After a while of blissful daily happiness however, I started to have irregular problems with both my screens blacking out quite randomly. It was odd and I couldn't tie it to anything. I went to the shop where I'd bought the PC, but they couldn't find the source of the problem – we swapped the graphics card and that definitely WASN'T the issue. I took it with me again and kept a protocol for about three weeks (on paper, which I have since thrown away), and in the end I went there again and they swapped the mainboard, CPU and RAM for me. After that, the error I'd been having went away. That was in June.

I have since had different sorts of odd errors, and my protocol (which is now digital) tells me that they're up to almost every other day now (less in the beginning). Sometimes they're quite serious, I've had some BusyBox fun twice, with the whole system freezing on me the first time (while in the BusyBox). Some errors which I've seen more than once:

• Both screens suddenly show the Asus splash screen that's normally shown only on boot, whole system frozen, needs hard reset. This has happened completely unprompted while the PC was utterly idle and doing nothing.
• The system freezes EXCEPT for the cursor which can be moved completely unhindered. Sometimes I can then switch to a terminal which will usually show I/O errors in between lists of systemd-jornald: Failed to write entry and Failed to rotate [...]: Read-only file system. This usually needs a hard reset as well.
• World of Warcraft (which is the one programme which might be a little taxing for the system) has become jerky in the last three weeks or so. I've had the system monitor app running for a few days now to see if there's anything remarkable, and I'd say the jerks always come with single CPU spikes… but sometimes not even up to 100%. Also it doesn't seem to be related to how much is going on in the game, how many people are around me or anything like that. AND! the jerks do not affect the cursor, at all. Plus… it isn't always jerky.

There are some other odd occurrences which may or may not be related, but the general feeling I get is – it's unprompted or it happens upon clicking an icon or otherwise asking any programme to do something simple.

Anyway, I've been thinking that all those hard resets in the last months (the previous no output problem would also be fixed with hard resets, and nothing else) cannot have done much good, so I thought I'd do a file system check. I've done quite a few of those in BusyBox prompts because I would also get these sometimes after hard resets (understandable, I'm sure).

My last BusyBox prompt and following successful fsck was on August 4. My system has two hard drives, one running Kubuntu and another with the home partition. I used a USB stick with a recent Debian live system which I had lying around, booted that (graphical output didn't seem to like my graphics card so I only had a terminal anyway), and tried to run fsck on both devices. It consistently says Bad magic number in super-block while trying to open /dev/sda (or sdb). I tried e2fsck -b 32768 /dev/sda (and 98304, 163840, 102400000, got a list of numbers from mke2fs -n /dev/sda), but with the same error.

Sooo long story short: my system is running ok with occasional glitches, but I can't check my file system. That can't be good can it?!

What do I do? Would a reinstall help? Could this be an issue where somehow my superblocks are set off a little (found that on the internet somewhere, can't find it right now though)? How likely is it that all (or most of) my odd errors are related to a hardware problem with the disk? Could ALL of this somehow be due to a faulty power supply?! (I've read these can sometimes cause quite random errors.)

Any ideas are much appreciated!