After some testing, I found out that it is best to print the support in PETG as the air inside a pc case might get hot enough to soften PLA.

Also, I recommend increasing your nozzle temperature by 5 ºC so there is better layer adhesion and the parts are more durable.

I couldn't find anything online that will fit in an M-ATX case while being able to support a hefty GPU so I decided to create my own. This support “screw” can be extended from 40 mm up to about 65 mm. On the bottom it has holes for five 5x1mm magnets that help it stay upright in the case.

The threads are standard M14x2 so, if you want to, you can easily create your own screw that can be longer.