If it make you feel better, I wondered why a new build wouldn't start once, I checked all my connections, took out the CPU, swapped RAM, etc. I found out I had accidently cut one of the wires to the power switch, so I had to use the reset switch as a power switch.
You GPU has its own fan to exhaust out the back plus the case fan (exhaust, yes?) above it, so it should be fine. The PSU needs cool air which is one reason I like the bottom PSU mount cases.