Case fan positioning advice - kinda troubleshooting.

Buying 2 Nanoxia Deep Silence 120mm PWM Fans to put into a Enermax Fulmo Q case. I've got the Asus R9 390 cutting the case in half in the middle.

Should I mount one to the top and one to the front? (case has great front ventilation and some fan mounts apparently), or both to the top corner? (case has 2 spots up there, one facing up and one facing backwards).

Case came with one slightly noisy fan mounted high in the back.