Well, it depends on situation.
Right now I am controlling some fans with gpu temp but because it is gpu pump and gpu rad fans (modded hybrid). Also I switched intake fans to look both cpu and gpu (and maybe even PCH) temps - but with huge hysteresis, so it will not react on some sort of temperature spikes. Monitoring air inside case is not working for me because there is very tiny difference between gpu at idle and gpu at 100% in "ambient" air temp. While on low rpm gpu can overheat very fast and easy.
So I placed thermal sensor under backplate above the gpu area. There is holes in backplate on both XC and FTW3:
You can try to place sensor under backplate above gpu using this holes. But you need to push sensor against pcb, it should not just hanging in the air near plate. So it must sit here tight and also this will protect sensor from pulling off hole.
And of course you should not apply much strength because there is elements on pcb you don't want to be ripped off the plate.
Sensor placed that way heating up a bit slower than gpu, but it is actually good reference for fan control. If gpu temperature is consistent - gpu sensors shows 5C less temperature and it is not a huge difference. So if your gpu heat up to 70C - sensor will be at 65C.
post edited by DeadlyMercury - 2019/12/11 05:42:25