Install case fan

English Hardware
1

I recently assembled a new barebone box. It came with its own power supply. When I tried to plug in my monitor to the new motherboard I discovered there was no on-board graphic connector. Back to the computer shop for a graphics card, something I have not had to consider since 8086 days. Nothing fancy, but the case does run a little hotter than I am used to. I have several salvaged fans and thought I might mount one on the case. But how? Web searches produced conflicting advice. Some examples…

Now, before we go about installing the fan, we need to figure out what we want to do with it. Do we want it to blow air in? Or blow air out? It all depends on your situation. In my case, I'll have one fan blowing in cold air but eventually that will get hot and raise the temperature in the case, so I'll want this back case fan to blow that hot air out.

Be mindful that the orientation of the fan should be so that it blows air out of the case; this in conjunction with the power supply fan sucking air into the case creates a vacuum that keeps air moving through and cooling the components.

A good rule of thumb is to orient the fan so that the manufacturer's label is facing the inside of the computer and the UL label is facing the front face of the computer. Mounted in this fashion, it will be an exhaust fan.

The tricky questions is - which way does the fan face? Well, at least for the Sunon fan, the fan should face with its label toward the case wall.

When I checked the power supply fan, it was blowing out of the case, so my immediate thought was to have the added fan blowing in. But wouldn’t that depend on the area of the vent on the side of the case? If the vent was small relative to the total flow it might add processor heat to the power supply. Blown out power supplies are not kind to motherboards.

Any opinions or suggestions? Thanks.

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> Any opinions or suggestions? Thanks.

if it were mine (and i could) i would mount the fan low and in front,
blowing in…

and i’d get that bunch of cables and wires undercontrol and out of the
way because i’d like the added fan to introduce cool air low and have it
flow over the motherboard and graphics card on its way to the rear
exhaust (the power supply, normally mounted high in the rear, sucking
air out)…

ymmv, and you will probably get conflicting advice

–
dd

3

Indeed. In a standard desktop I’d have one in lower front blowing air in and another just below the PS (i.e., as high as possible) blowing air out. Warmer air goes up, as every balloonist knows :).

If you have only one fan opening, it’s usually better to blow out than in. But obviously the best is to try both ways: first install the fan blowing in and check temperatures (usually CPU and MOBO temps), then invert and compare. It depends on fan placement, but it’s probable that out will be better. If you have inverted results (like CPU temp goes high while MOBO’s lowers) then You’d have to consider what’s best for you - sometimes trading +1 ºC on CPU for -5 or -6 ºC on MOBO is a better choice.