My first PC ever built is sort of unusable in its current state, and there are a few things I could do:
- Update necessary parts and keep it as a retro-media-compatible PC/nas/server. I love how it has a floppy drive!
 - Get rid of it and save money
 
If I wanted to replace it, I would need to get at minimum:
- motherboard
 - ram
 - CPU
 
I’m hoping I can keep using the following parts, some of which have been updated over the years:
- pcie 2.0 graphics card
 - 500 W power supply
 - monitor / peripherals
 - optical / floppy drives
 - SSD / HDD
 - ATX case (the original case and motherboard PCI slots never lined up quite correctly…) Cooler Master centurion (?)
 
I’ve never done anything like this, and last time I built a PC was in 2006. I lack a lot of knowledge…
- Is my case likely to be compatible with a modern motherboard?
 - Can I buy a modern motherboard/CPU that will be compatible with this other stuff?
 - Would it be less expensive to buy another used PC and use its motherboard/CPU ?
 


Decide your budget first, everything after that follows. Most likely like others have said ignore that old pc, you get get something much better second hand for very cheap.