I'm not a heavy linus user so I can't help with the linux specific stuff but here's some general comments.
I would get a higher wattage PSU to be safe. The 3000 series can have high power spikes and even without spikes the 3090ti can consume 600 W on it's own.
For your old drives I would get a docking station like this: https://www.amazon.com/dp/B07WS59SP4/ It's easier to just put them in the dock than to install them in an enclosure.
For audio I would go with an external DAC instead of something integrated.
You could save a lot of money on the motherboard. Pretty much every b550 or x570 board with 4 memory slots is also compatible with 128 GB ram.
With cases you're pretty limited because not a lot of modern cases still support optical drives. The fractal design pop air case is one of the few modern cases that still support it and it has a kind of boring look.
So far I’m loving them, they were $27 on Amazon. SSK brand, and kind of cheap feeling plastic, but so far they’ve handled multiple TBs of read/write and have no noticeable speed issues so that’s a definite plus.
It sounds like your HDD has failed. You may get lucky and have it be recognized, but I would not trust it for very long, if at all.
I have heard of people having a bit of success by placing the HDD in the refrigerator or freezer for a bit to bring down its temperature before trying to access the drive. Of course, I recommend using an external drive bay for access, such as this, or something like it. Good luck.
This type of device is great cloning, but better to get one that can support 3.5" HDD. My choice was this one:
For a hard drive, you need the extra power of a wall outlet. If it were a solid state drive, USB would be enough.
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This would work (as reference): https://www.amazon.com/SSK-Aluminum-External-Duplicator-Function/dp/B07WS59SP4/
Very much possible that your hard drive could be failing.
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I'd advise two things.
1.) In that command prompt, attempt to do chkdsk /f C:
This scans your hard drive for any errors. This might take a while to do.
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2.) If that doesn't work, you may need to get a new hard drive and try to pull any data off of it using something like an external hard drive dock. Something like this:
https://www.amazon.com/SSK-Aluminum-External-Duplicator-Function/dp/B07WS59SP4/
note: you only need this if you want to save media files such as pdfs, pictures, videos, music, or anything else. programs and games will all have to be reinstalled.
But then you would need a working computer which would involve a new hard drive (probably an SSD would be a great choice).
Yeah... I am considering the following hard drive dock to replace one that is probably around 10 years old and only supports 2TB drives. This one supports up to 10TB hard drives.
That's what I do. I basically use hard drive docks to mount 2.5" and 3.5" hard drive for extra storage. Note that they are not portable since they need to be plugged into the A/C outlet for power. Below is one that I am thinking about buying to replace one of my docks that is probably about 10 years old by now and only supports up to 2TB drives. The one below supports up to a 10TB hard drive.
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If you prefer to use as "portable storage", then you can buy a 2.5" drive enclosure for it like the following random one I clicked on.
It's super simple. A 2.5" drive cloner are $20-$30 on Amazon and it just duplicates the source to the destination on a block by block level.