Rinsworth

You can potentially have it run in the background as an ethereum miner, but that might not be the best idea, as it would use a lot of power and create a lot of heat. In more practical terms, you can run a second monitor with the 750 ti as a dedicated gpu for it.

If other 1060s work, then it may be the card rather than the computer.

The first thing to do is to reinstall your drivers. Use DDU and then reinstall whatever Nvidia drivers.

Just check that the Ram works. The HDD will be fine.

Yes. All that stuff is pretty much enthusiast grade. The PSU might be a bit overkill, but everything else is above good. You can probably max all the settings and have a framerate above 70 FPS. Just make sure to plug in your display cable into the GPU, rather than the motherboard.

If the build is just for school and such, you should consider using an SSD rather than, or alongside, the HDD. It makes life a lot easier, and will help considerably more than a better CPU or GPU. Also, if she's running Windows 10, the computer will probably need 8GB of RAM to work well, or it could bottleneck the rest of the components.

If you had all your music uploaded to the cloud, then there is an option in the settings that lets you download everything at once. This would download everything onto whatever you wanted. I'm not sure if this option is available on the app, but this would quickly get it onto a computer, where you can then move the files onto the SD card.

Well, 15-17-17-35 looks like the default if you look online, but the lower timings are better. Why not try them?

Something around this ballpark is definitely good for what you're selling. Anything higher is pretty much scamming out the buyer.

Ryzen works well, and the amount of cores can let you set certain cores to run certain things only (game server on cores 0-3, plex on 4-5)

https://gpushack.com/ is a good place to get GPUs refurbished. In most cases, used GPUs are fine unless they've been used for crypto-currency mining. Just check online for a pricematch or something.

Most likely you need to go to storage devices, or disk management, and format it yourself. In some cases you don't need to, but in any case it would always be beneficial to reformat the drive.

RGB looks nice, but yes the craze is fairly intense.

Timings should change when you change the RAM speed, but you can manually adjust them. 2400Mhz, for example, can be put at 11-13-13-31, but it is possible to tighten the timings down further.

There are adapters that are used for these cases. They are fairly cheap and most of them work ok at best.