Here is what I try to explain :
Fig. 1 = PSU is rotated, its fan is front of the RTX 3080 fan. Imo, warm air has more difficulty evacuating.
Fig. 2 = PSU is mounted on the bottom of the case with its fan in its original position (motherboard side). Imo, warm air is easier to evacuate because there's more space around the gfx cooler. Besides, if there is enough thickness, maybe we can put a fan at the top.
Note : my scheme is not scaled, I did not take into account the problems related to the power cable of the PSU and the USB port in the bottom...
Fig. 1 = PSU is rotated, its fan is front of the RTX 3080 fan. Imo, warm air has more difficulty evacuating.
Fig. 2 = PSU is mounted on the bottom of the case with its fan in its original position (motherboard side). Imo, warm air is easier to evacuate because there's more space around the gfx cooler. Besides, if there is enough thickness, maybe we can put a fan at the top.
Note : my scheme is not scaled, I did not take into account the problems related to the power cable of the PSU and the USB port in the bottom...