New Fan? Which Way Should It Blow?


So you’re just about to bolt on a new fan to cool your UberMach 3000 rig. All you need to know now is if the fan should be an intake or exhaust. You hit your favorite forum and ask to find out. What ensues is a surreal exchange turning into a flame war with math and theory only Einstein could figure out. Terms like air cavitation, laminar flow, dead zone, chaos constant, negative and positive pressure, stabilizing collimator, flux capacitor, and Heisenberg capitulator are thrown around like “ Expelliarmus ” at a Potter festival!

Were you Nutz?! Did you not know that such questions should only be left to level 21 and higher geeks with at least 200 hit points? One misplaced calculation and a reversed fan can cause a rip in the Universe! What were you thinking about ?

In all seriousness, these things get out of hand, or in depth, for a number of reasons. One reason is that getting good flow from scratch in a case is deceptively difficult. Another reason is that geeks like to argue and use big words. But, if all you are doing is installing one fan into a case that already has cooling, consider the following a guide:

If you are trying to cool a specific part – like a window fan right over the CPU – the air should blow in (intake fan). If you are generally trying to cool off the interior of the case, the fan should blow out (exhaust fan) if it is on the top half of the case and inward if on the lower half of the case.

Don’t believe me though.

I’m serious by the way – you shouldn’t believe me - it’s imperative! Potter and Middle Earth depend on you doing the exact opposite of what I say! Otherwise the Dark Lord will find The Ring II ( now available on DVD ) and all is lost!

Do not believe me because, while I am probably right, there are too many variables to be sure. So, install your fan(s) the opposite way from what I recommend and boot up. Use a program like Everest Home Edition or SpeedFan and check the temperatures as you ramp up to load on the CPU, GPU(s), case, and so forth (whatever sensors are available to you from the software). Then, shut down, flip the fan, and repeat. See which temperatures are cooler. If I was right, you are finished at this point. If I was wrong – well, just flip the fan once more and call me funny names. If you are installing more than one fan, you may have to try a few more combinations.

That's about all there is to it. True, it's a simple tip, but it often gets lost in all the "theory" out there. And yes, I did gloss over all those important concepts like “balanced flow”. Sometimes “what works” is more important than “what should work” though.

So, is it an innie or an outie? Well, it’s your patient – you decide doctor!

This week’s bling was spotted a bit back by MPC forum member Gamerfreak. Not strictly a computer mod, but a modded singing Tesla coil . BTW – that’s not just a special lighting effect. The arc generates the sound.

Happy Moddin’

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