Installing a Power Suppply in my old Desktop

Justine sent me an old desktop computer about 10 years ago. It is a little slow and old and over the last year it has started making fan noise an overheating. I considered buying a new desktop, but they go for about $600-$700 for the one I wanted. I vacuumed out the fans and it ran well for a few months, but it started making horrible noises again.
I bought a NVIDIA video card (because it has a fan). I bought a nice 1 TB ssd. I also bought a power supply on eBay. I had to return the power supply because it was not compatible with my computer, even though it was advertised as thus. I returned the power supply bought an inexpensive one (that cost less than the eBay one).
I replaced everything and now I have a very cool, very fast , quiet system. The ssd makes a huge difference in the speed of my 10 year old system. The NVIDIA card also seems to make all the graphics much faster. The power supply is twice the wattage of the old one.
I now have an old system that may be good for another 10 years for about $150.
Pretty soon I will be wandering the back roads of Rockland County and I might find a nearly new desktop computer in the junk. I’ll just transfer my hard disk to the new machine and have an even newer machine. The older machine might be good to run a local security server that runs a DNS server and VPN or maybe a media server.