Fan Placement Advice

[evilpizzaman]

 

I recently inherited a water cooled 1080 Ti from a friend, and had a hell of a time trying to make it fit into my Fractal Define C. Right now this is what it looks like, with the rear (orange) and front (rad) fans as intake and the top fan and PSU as exhaust. CPU cooler and reservoir placement is non-negotiable; this is the only way it'll fit. A concern I have is the clearance between the rear intake and CPU fans. I feel like I read somewhere once that there's a lot of inefficiency with a gap that small between fans. Am I remembering correctly or is that just something my mind made up? Additionally, if I moved the intake fan to the top, directly above the CPU cooler, would that be better, or would that mess up the airflow of the entire case with a top intake right next to a top exhaust?

[Fasauceome]

40 minutes ago, evilpizzaman said:

with the rear (orange) and front (rad) fans as intake

 

40 minutes ago, evilpizzaman said:

the top fan and PSU as exhaust

I am guessing the CPU fan is not blowing air in opposite direction to that orange fan.

 

Otherwise, this system does have some competing airflow that you may want to do away with. Considering the front intake and rear intake are blowing opposite directions, and the PSU and top exhaust are blowing opposite directions, the fans are basically all fighting one another.

 

Now depending on how well perforated your case is, you are still basically fine due to good positive pressure, but if it were me, I'd set the rear fan and CPU cooler to blow air out the back, and then flip the power supply to have its own air flow (your case's feet will elevate it appropriately for bottom intake.) The top fan will pull some hot air right off the radiator, and the rest of the air will flow back over the CPU cooler. Slightly worse thermals due to the heat off the rad, but it should be fine.

40 minutes ago, evilpizzaman said:

feel like I read somewhere once that there's a lot of inefficiency with a gap that small between fans.

Wouldn't worry about it.

 

40 minutes ago, evilpizzaman said:

if I moved the intake fan to the top, directly above the CPU cooler, would that be better,

The top exhaust would put some hot air out, the top intake right next to it would suck some of the hot air right back in, so it would be less efficient in this case. Either two top intake or two top exhaust would be practical.

[brob]

I would move the rear fan to the top as exhaust. Reverse the cpu cooler fan so that it pulls air directing it out the now open rear fan position. I would also isolate the PSU by inverting it so that it draws air from the bottom and exhausts out the rear.

 

There can be issues with inline fans that are close to each other. One fan may force the other to spin at a different rate.

[evilpizzaman]

27 minutes ago, Fasauceome said:

...the rest of the air will flow back over the CPU cooler. Slightly worse thermals due to the heat off the rad, but it should be fine.

Under normal circumstances this is what I'd do, but I have a pretty substantial overclock going and have CPU temps averaging ~70 w/ peaks at almost 80 degrees under load, so I'd like to avoid this if possible.

[Fasauceome]

2 minutes ago, evilpizzaman said:

Under normal circumstances this is what I'd do, but I have a pretty substantial overclock going and have CPU temps averaging ~70 w/ peaks at almost 80 degrees under load, so I'd like to avoid this if possible.

If your thermals are satisfactory as it stands, the only thing I might recommend is two top intakes and a rear exhaust. 

 

As always with airflow, experiment to make sure the changes you made are actually impacting you positively. The ambient conditions of your room specifically will be unique, and not every suggestion will perfectly take that into account.