I have never had fan speed or number of fans make any kind of difference with temps. My current setup is two 120mm intakes at front, one 140mm exhaust at top and h60 in push pull at rear as exhaust. The case fans are connected to a fan controller. With them at lowest setting (so slow you can see the blades spinning), the CPU and GPU temps at load are identical to the temps when the fans are going full tilt. No difference at all, not even 1 degree. I also tried adding another top exhaust which changed nothing at all and a side intake that actually raised the GPU temp by 2 degrees.
The system sits at 57c-CPU and 74c-GPU at 100% load for both for infinite time no matter what the fans do. Also switched the h60 to intake for laughs and nothing changed but the GPU ran 1c hotter presumably because the h60 was blowing the hot radiator air into the case. I changed it back to exhaust and left it like that.
weird.