Should your power supply fan face toward the inside of the case?

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LB3

LB3

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Apr 25, 2014
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I have an older Corsair TX750 (non-modular) bottom mounted. The bottom of my case (Corsair 400R) is vented for the PSU. Almost every build I see on the interweb shows the PSU with the fan pointing into the case. What's the deal?
 
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https://www.reddit.com/r/buildapcsales/comments/2tbwzx/power_supply_evga_g2_750w_80_gold_fully_modular/

http://forums.hexus.net/psus/244541-haf-x-psu-up-down.html

Good discussions here, plus don't know if anyone has cleared this with you, but the fan is set to suck air into the supply and exhaust it out of the back of the psu whichever way it faces...

I want to avoid accumulation of dust so I point up, because I have provided reasonable protection against dust ingress into the case..

plus those downward openings are a tad restricted on the 300r.. so again I went with it pointing up.. considering how OCD I am, I have gone for the less elegant solution because to me it just makes more sense.. the fan barely spins pointing up...
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99.9999 (100% really) of bottom mounted cases should have the PSU fan vented through the bottom of the case mate - this isolates it from the rest of the system.

The only scenario where I'd face the fan into the case is if your PC is going on the floor on deep pile carpet.
 
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Thank you! I've had it facing "down & out" since I built the PC then noticed all these newer builds with fans pointed inward... It makes complete since. But, I noticed that manufacturers may be partly to blame because, on some models, to display the PSU logo and text right-side-up the fan must be pointed "up & in." Fortunately, my PSU has the fan on the bottom with the logo and text upright (forethought was put into this model).
 
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^^^ +1

With a bottom-mounted power supply, if you put it fan-up, it will be drawing hot air in from inside the case. It'll also be fighting the fan on your video card and drawing airflow away from your CPU, and both will suffer for it.

As mentioned above, the reason for a bottom-mounted PSU is so that it draws in cool outside air and doesn't get involved with the airflow in the rest of the case.

One last reason why you do not want it with the fan facing up is that if you are ever working inside the case and drop anything - a screw, for example - guess where it's likely to land. You do not want to operate your PSU with a screw inside it, and you also don't want to poke around inside it to get it out either.
 
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I appreciate everyone's input in confirming my suspicion. But now someone needs to educate these PC builders - if you Google "Custom PC Build" and look at the images, it's rife with upside-down PSU's, primarily with the logo upright.
 
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I have the Corsair 300r case which like the 400r makes provision for a bottom mounted psu in-taking air from underneath the case. However, I have installed the psu with the fan pointing up into the case. Why? because it seemed more logical. Why? Because if placed the way Corsair intended then the populated pcb is essentially upside down which does not allow for optimum convection, plus do you really want to keep fishing out that filter every few days or so? I'm with Johnny guru on this one i.e.bottom mounted psu fan pointing upwards inside the case is best....

Since the psu is on the bottom of the case where the air is cooler, and with 2 x 140mm intake fans, warm air is not an issue...

The psu is obviously a compromised legacy design and so I believe upside down with the fan pointing up is best.

PS: most psu's these days have the sticker placed one way on one side and the other way on the other side...
 
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Very good point. Do you have the Johnny Guru link? What prompted me to start this thread, besides all of the pictures of inward facing PSU's, is that on second look my legacy PSU may be designed for top mounting with the fan facing downward and into the case. Either way, this is not a personal concern, just a general discussion.

(5 x 120mm intake (front, bottom, side), 2 x 140mm exhaust (top), 1 x 120mm exhaust @ 3k RPM (rear))
 
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^ atx psu's have been a uniform design for 20 years +.
The screw Mount holes have always been symmetrical meaning you can mount up or down but past 10 years you won't find a single case with a bottom PSU mounting.
Top mounts were the norm hence the design - the PSU fan was designed to also act secondarily as an extra exhaust for the CPU.

Mounting with the fan upwards in a bottom mount case will obviously 'work' fine but it's not the optimal way IMO.
 
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Absolutely, I'm in the same boat as madmatt and capt_taco - the fan should be used as exhaust. What I meant by my legacy PSU design is to keep the logo upright the fan must point down which would have been standard for top mounting and works perfect for exhaust on a bottom mount.

My observation is that almost all PSU models, with the logo upright, have the fan on "top." This would cause the fan to point inward and is also in-line with GarSpear's point. So why would manufacturers make PSU's you had to flip "upside down?"

This may be been a carryover from top mounting where the fan usually faced downward and into the case but it's sounding like manufacturers are building units to have the fan face inward/upward.
 
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I think what you'll find with decent branded PSU's is that they have the logo on both sides of the PSU in opposite orientations so the logo is always showing the correct way no matter how you place the PSU - the corsair ones on newegg do show it how you say but I know for a fact they also have the label on the opposite side as well.
 
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If there is a ventilation grill on the bottom of the case the PSU fan faces down.

zyik9.jpg


 
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I still believe fan facing up is best especially on psu's that ramp up or down depending on load. The psu is obviously a legacy design i.e. very compromised, not ideal anymore. Likewise graphic card designs make little sense to me.. why is that fucking card upside down? Lots of compromises. Things that have evolved
but would likely be designed different were it not for legacy sizes etc...

With the fan facing down the populated pcb is upside down, so you do not benefit much from heat loss due to convection. My psu fan seems to spin less and slower when placed fan upwards.. and my motherboard and CPU are barely 5 degrees above ambient. Thus if the psu is warming up the case, so be it, it's hardly making any difference with 2 x 120mm exhausts and 2 x 140mm intakes.. plus two x whatever they are on my r9-270x.. none of which are running more than 50% max speed.

Try both ways.. it's only going to take a few seconds to change it you change your mind. It's your choice. ..but cleaning filters is a pain in the arse IMO. I just want to point a vacuum cleaner at the front now and then and maybe a brush with a clean big paintbrush and regular vacuuming of the carpet.. that's my style....

http://www.jonnyguru.com/forums/showthread.php?t=12623

I see you have asked your question there. Johnny Guru has worked for Corsair I think.. he prefers up.. some prefer down.. I have a carpet and put my pc as close to a back wal as possible between a side wall and a book case in the corner of the room, so I chose up.. I don't want to pull that case out much.. I want to leave it undisturbed..

As to dropping screws... I agree.. if you drop a screw you could potentially be in for a fright when it goes bang... I had a beautiful looking Tagan go bang years ago.. my Enermax 650W noisetaker lasted for 10 years of pretty much 24-7 use and just failed, no bang, no damage.. why are they not the top guys any more? That noisetaker was built like a brick shit house.. all the pcb tracks had extra solder tinned in to them by hand..

.. but I have used ladies stockings and thin porous packing material as ghetto filters on my case and you could buy or make a thin filter to keep screws out.. . but does it really matter? Down looks better I spose if you have a window... but I don't like windowed cases, well I do, but I don't want one.. I prefer just a little glow on one fan on the front.. too many led lights on things these days I think.. I keep it to a minimum.

aw feck it.. I'll post pics of what I did later.
 
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https://www.reddit.com/r/buildapcsales/comments/2tbwzx/power_supply_evga_g2_750w_80_gold_fully_modular/

http://forums.hexus.net/psus/244541-haf-x-psu-up-down.html

Good discussions here, plus don't know if anyone has cleared this with you, but the fan is set to suck air into the supply and exhaust it out of the back of the psu whichever way it faces...

I want to avoid accumulation of dust so I point up, because I have provided reasonable protection against dust ingress into the case..

plus those downward openings are a tad restricted on the 300r.. so again I went with it pointing up.. considering how OCD I am, I have gone for the less elegant solution because to me it just makes more sense.. the fan barely spins pointing up.. great. If my motherboard is barely 5 degrees above ambient.. the psu is likely not much more than that... and less dust! and no need for weekly pull outs of the pc from its place.
 
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