Just came across your question. I shorten the USB cables on WiFi cards and RGB controllers regularly. It's basically the same process as making ATX cables. The terminal used is a female 0.1" pitch header. The wire is much smaller, so it's harder to get a good crimp that will both stay on firmly and fit back into the connector. I use this micro crimp tool to help snug them up.

Let me know if I'm not explaining it well or you have any questions.

You will need crimpers like this one too

https://www.amazon.com/gp/aw/d/B078WNZ9FW?psc=1&ref=ppx_pop_mob_b_asin_title

They are a bit of a pain to put on until you get the hang of it. Practice before you do them on the fan.

It’s very easy to crimp new connectors if you have the right tool. And you will find that a crimping tool and spare connectors comes in very handy with a 3D printer.

The connectors are JST-XH and you can find kits on Amazon. But don’t buy the kits with a crimper because those tools invariably suck.

The best inexpensive tool I’ve found is the IWISS IWS-2820M AWG 28-20 for around $20. If you want to treat yourself, the Engineer PA-21 is around $50 and by all accounts an excellent tool.

Whatever you do, don’t buy a tool that crimps both the conductor and the insulation at the same time. They rarely work well and break easily.