The question your probably asking is... what is the effect of using heated rad air as intake air vs setting up rad so you expel air out of it. I have tested this in past using multiple configurations and posted this on another forum. And short answer to your question, if you have ample rads to ensure decent delta ambient air to water is ~5-6C, and decent fan speed 1500rpms or more at load, then temp is going to be only ~2-3C hotter after going through rad, using accurate equipment to measure. As to effect on various computer components of rad air as intake vs expelling air out rad....
I have 280 rad in front and a 360 rad up top, both rads with push/pull fans. I used 12 calibrated dallas probes, 1 at each fan intake, and 1 in water, and 6 inside case at equidistant spread out locations, each logged per 1 second, relative accuracy is to 0.1C.
I tested using
1) both rads (top and front) as intake air, (best cpu, gpu, nb, ram temps), expelled out rear GRAPHED IN BLUE below
2) both rads (top and front) exhausting air, (poor performance, not graphed)
3) front rad as intake and top as exhaust. (best mobo, hard drive temps by 1C) GRAPHED IN RED below
The one that gave the best cpu, gpu, NB, RAM temps but ~1C worse mobo, hard drive and inside case temps was using both rads as intake and expelling air out back, and that is what I went with. The next best was using front rad intake, top exhaust which gives slightly better 1C or so mobo, hard drive and inside case temps, but worse cpu, gpu, nb, ram temps.
The three graphs all show front rad + top rad as both intake in BLUE (air exhausted into case), vs front rad intake but top rad exhaust in red:
graph 1 is prime loaded max fan speed,
graph 2 is prime loaded quiet fan speed,
graph 3 is prime + furmark loaded max fan speed. Gaming was too variable to test well, but average inside case temps were nearly same with either config, so again, cpu/gpu etc would be cooler just from lower ambients.
The reason cpu, gpu, temps are better when pulling cooler outside air through rad is self evident... air outside case is always 2-3C cooler than inside case regardless of configuration, so 2-3C cooler "ambient" intake = 2-3C cooler cpu, gpu temps.
The NB/ram temps may seem paradoxically cooler by expelling rad into the case, but it is only cooler if the top rad has pull fans inside the case, as this fan air hits the NB/ram heatsinks, and pulling air above the heatsinks seems not to affect temps much, pushing air over them makes a big difference. (MOBO and HD were either same, slightly cooler or hotter, if fan speed maxed/not and depending on location of HD relative to closest fan).
The temp difference inside the case of all 6 probes comparing exhausting rad air out of case vs into the case was never more than 1-1.5C. And average between all 6 probes was typically 0.3 to 0.5C difference. Reason is air going through rads is only 2-3C max hotter air than ambient. And temp inside case is always hotter than that from heating from caps, etc on mobo, gpu, nb etc heating inside of case.Bottom line you will get 1-2C better cpu/gpu temps, variable better RAM/NB temps depending on fan speed, at expense of ~1C worse mobo/HD temps by using both rads as intakes, assuming pull or push/pull on top rad. So either configuration works fine.
NOTE 1) if fan speed is high enough, mobo ambient may be variable either way by 1C depending on where you measure. NOTE 2) If doing something crazy like fully loading 2gpus/1cpu at 600 rpm fan speed, your cpu, gpu temps will still be lower by 1-2C taking in cool outside air, but then you can increase all internal components by few C by exhausted rad air in case vs out of case, but not in real world use, ie gaming at 800 rpms.
graphs of above testing: