I printed a case for a small PC that I user as a home server 3 years ago, and I used the cheapest PLA out there. No warping, nothing broke. It is cooled by a single 80mm.
As long as there's enough airflow to prevent the PLA from actually heating up, it will be fine.
I was also worried about that, but for this PC its only sun that can melt it haha. But yeah it would be better to print with petg or abs
Cpu temp never goes above 45C lol. Usually at 35 and case fans are not even spinning. Also mbo is "raised" 10 mm from back wall if that make sense.
I've also had problems with PLA prints delaminating and becoming brittle over time, especially if it's being flexed or exposed to sunlight. Some PLA's are worse than others with this, though.
I use PETG for anything I want to last a long time.
MBO: MSI Z270-A PRO
CPU: Intel G3930
RAM: DDR4 8GB
PSU: Corsair RM550X
FAN: 2x Arctic F12
3x SSD for OS and storage
Most of components were laying around and I wanted to build low power server. Its pulling 20-30W from the wall and its more than enough for my needs (media server, home assistant and some other lightweight apps), but I might need to upgrade RAM if I continue adding services 🙃