Also worth noting: JVS uses a USB cable to carry signal, not a serial cable. You should not have a JVS board directly connected to any COM port on the motherboard regardless of the actual JVS I/O board or PC(B) you're plugging it into. The JVS I/O board should have a USB B connector, which you...
I've gone and done something similar.
Similar to OP, I couldn't find a decent 3 pin 70mm fan to just replace the fan on the existing CPU cooler, so I just got a cooler master A73: https://www.newegg.com/cooler-master-air-cooler-series-a73/p/13C-000X-00010 (you can find them on ebay as well)
A...