PSU Airflow & PC Cases

[EagleDesignInc]

As far as the PSU, how should I place it in order to keep a positive Airflow on the cases?

See Figures 1 & 2:

Option 1: Have the PSU intake air from the system out

Option 2: Have the PSU intake air from the bottom (assuming case have a window for the PSU)

Thank you

 

[bloc97]

If you have a top-end GPU, it will suck air at the same location than the PSU, you will have a problem in that place.
Usually the PSU sucks air from the bottom to keep it very cool. The PSU needs more cooling than the other components, since a overheating PSU can damage everything.

-Bloc97

 

[mrt3]

the option 2 is better,
Your psu will get fresh and cooler air from outside instead of option 1 where, there is no more room for air after CPU GPU installation and your psu will generate more heat and make all the component overheated quickly

 

[EagleDesignInc]

If you have a top-end GPU, it will suck air at the same location than the PSU, you will have a problem in that place.
Usually the PSU sucks air from the bottom to keep it very cool. The PSU needs more cooling than the other components, since a overheating PSU can damage everything.

-Bloc97

Yes I do have an GPU with dual fan. Thank you for the input.

 

[The Original Ralph]

as others have said, option 2 with psu taking its air from the outside for the additional reason:

too many devices taking air from the inside and exhausting it, can cause negative air pressure inside the case, which means cpu fan will struggle getting air to move over the cpu heat sink

 

[bloc97]

as others have said, option 2 with psu taking its air from the outside for the additional reason:

too many devices taking air from the inside and exhausting it, can cause negative air pressure inside the case, which means cpu fan will struggle getting air to move over the cpu heat sink

Negative pressure also means that air from outside will want to go inside the case. The rear fan will have much more difficulty venting all that hot air.

 

[The Original Ralph]

yes it will, but just because it "wants to go inside" doesn't mean it helps create an efficient cooling environment - not having negative air pressure means the cpu fan will have an easier time pushing air thru the heatsink fins - why would you want to tolerate much less create an environment that diminishes cooling efficiency ?

and " .....The rear fan will have much more difficulty venting all that hot air." You might want to rethink that point - it actually re-inforces what i'm stating - by not having negative pressure inside the case, that rear fan will have an easier time pulling air out

 

[EagleDesignInc]

What about the cases that don't have the bottom window for the PSU, It will have to be placed just like on Figure#1
I've seem new PSU models with Led lights, they are meant to be placed with the grill fan on top (sucking air for the system)

 

[The Original Ralph]

below is a shot of a SFF (small form factor) computer i'd built and was when it first occurred to me re the shortcomings of a PSU drawing air from inside the case.

This is an extreme example of what i was referring to, but even with 2 80mm fans blowing in, and one 80mm exhausting, my temps were too high (i7-4790) - the PSU's fan is 140mm and a pretty serious cfm fan, from the volume and pressure of the airflow to my hand at the exhaust side at the rear of the PSU. Large high cfm fan sitting 1 & 3/16" above an anemic 80mm intel heatsink fan, no question which fan gets the air. The PSU fan was creating a heckuva negative pressure zone just over top of the cpu fan.

The situation with high temps on the cpu got slightly worse when i added a graphics card w/2 slim 80mm fans also pulling air from inside the case and exhausting it out. I ended up adding three 60x25mm fans blowing directly onto the cpu and motherboard from the opposite side of the case (opposite from the camera). Even with the case having open grills running full length on both sides the cpu temps didn't drop until i popped those 3 60mm fans in. The computer case btw is a silverstone sugo sg02 - why silverstone chose to design the case so it mounted over top the cpu and drawing it's air from the cpu area is beyond me - i looked at flipping the PSU so it would intake from above but that would require cutting a grill opening in the case top and fabricating a mounting plate as the mount opening and the screw placement is asymmetrical - way too much work/time involved.

I thought about building a short 6" tall "base" to place under the SFF case, sort of a modular addition, and placing the PSU in it, with the inlet facing downward - probably the easier fabrication solution but still time/effort costly. Then i found this aerocool case, with the PSU placed the way it should be:

it also didn't hurt that the aerocool DS cube case is damn good looking, even if it did take up twice the volume of my SFF case

- if you think about it, why hinder the cpu getting all the air it can by creating negative air pressure (no matter how slight) and using warm air to cool the PSU when you can avoid both those scenarios

as to "....I've seem new PSU models with Led lights, they are meant to be placed with the grill fan on top (sucking air for the system) " - think about the priority of that psu mfgr - if looking "pretty" is the priority, the "gimmick-try" of that shouts volumes - no offense to the gamers that like to put on light shows inside their computer cases
fwiw