Fan placement - does it matter?

[ElB]

I've finally finished* my new build, but I didn't really have a strategy when I started so it's a bit of Frankenstein, and I'm not sure about my fan placement. As far as I can tell as long as air is moving you're pretty much good, and the CPU and GPU are water cooled so I'm probably fine anyway, but I'm still having a lot of debates with myself.

My case (Thermaltake View 27) has five fan mounting points -- one top-rear, three at the front, and one at the bottom -- and currently I have the radiator for my MSI Seahawk X venting to the rear, a Corsair H45 radiator venting through top-front, and then two beQuiet fans mounted as intakes below that (one running at constant full speed, the other controlled by motherboard temp).

Temps are good, but the thing that bugs me is that there's no consistent direction of airflow -- I'm so used to the "in at the front, out at the back" deal that it just doesn't feel right not having air flowing through the case in one direction, and part of me wants to mount the two radiators at the front, put an intake at top-rear, and have the third fan at the front as an exhaust -- that way air will just flow from back to front and I'll have more exhaust than intake pressure to keep the pesky dust at bay.

(...and this is why I gave up building PCs 15 years ago.)

* Still mucking about with lighting, I may replace the PSU with a modular one so I can use prettier cables, etc., but all the expensive bits are done!

 

[VKleita]

If Im reading that right , you want negative air pressure? (More out than in) usually its the other way round, then at least you know WHERE the dust is coming in , rather than just any crack or crevice it can find.

The only other thing i will say be careful with the "Its water cooled so I dont need air" The mainboard, Ram and SSD's etc still all need at least a smidgen of air movement to carry away excess heat, VRMS on main boards can also get very toasty...

 

[Glanza]

I've always gone with in and the front / bottom and out at the back / top for airflow. I still use this setup currently even with 3 rads in there.

 

[ElB]

The "always running at full speed" fan is blowing directly on the motherboard heatsinks, and running AIDA64 stressing CPU and GPU for 15 minutes the motherboard temp sits at mid 30s (although I have no idea where the sensor is) and PCH hovers around 50, with CPU maxing out at 65 and GPU staying at a frosty 45. My "it's watercooled, so no worries" was more to do with the fact that I'm dumping most of the heat outside rather than having a CPU fan filling the case with hot air, and given the ridiculous size of the thing I suspect plain old convection is enough to keep the inside from getting too warm.

(On the other hand, on the face of videos like this it appears you've got to try pretty hard to screw it up so I'm inclining towards keeping my current layout more for aesthetics than any particular technical reason.)