PC fans - suck or blow?

[steveathome]

May sound silly, but after replacing a faulty case fan on my PC, which way around should it fit?

My way of thinking is that is should blow / take hot air out of the system rather than suck ambient air in.

Does it make a difference?

[Jon]

You should have one pulling new air in and another pushing old air out. See which way your power supply's moving the air, for starters.

[JRJay]

It depends on the layout of the case. I would use a temp monitoring tool like speedfan and see which way results in a lower temp for the cpu/video card/hard drive etc.

[mellowd]

It all depends. generally you want air sucked in and then blown out the other side, so it creates wind inside the case. See the direction that the air is currently running through and then go from there

[Vitruvius]

On the one I use currently I have a fan on the side and in the front that suck air in, and in the back to blow air out.

So depends on placement and what your other fans are set to do.

[Tom W]

Depends on which fan it is - if it's the one at the back of the power supply, you definately want this one blowing out since the power supply generates a fair amount of heat. You probably want a flow-through scheme, but you want to push the heat of your warmest components out of the case, rather than swirling it throughout the case before exiting.

As someone else said, generally, draw cool air in the front, and blow the hot air out the back.

IMHO - I don't build 'em, I just use them.

[nicksan]

Front fan = suck in the cool air
Rear fan = blow out the hot air.

[Eagle]

Front fan = suck in the cool air
Rear fan = blow out the hot air.
Top fan = out
Side fan = in

Power Supply blows out the back also.
All this creates a nice smooth air flow out the back.

[steveathome]

You should have one pulling new air in and another pushing old air out. See which way your power supply's moving the air, for starters.

Good thinking,
Many thanks

[Woolburr]

May sound silly, but after replacing a faulty case fan on my PC, which way around should it fit?

My way of thinking is that is should blow / take hot air out of the system rather than suck ambient air in.

Does it make a difference?

Just some quick guidelines from an article in PCMag sometime back...Any fan mounted in the lower half of the case should blow in. Fans located on the front or the sides of the case should blow in. If the fan is located in the rear of the case, it should blow in if located at the bottom and out if located near the top...Any fan on the top of a case should blow out.

[steveathome]

Both my case fan and psu fan are both mounted on the rear.

The psu blows out, so I have followed Jon's advice and turned the case fan around to suck in.

All ok so far and now melt down as yet :)

Thanks to all for the advice.

[Zepher]

My 120mm CPU fan protrudes out of the side and blows out.
I have a 120mm fan mounted low on the front pulling cool air in.
On the other side of the case where the PSU and hard drives are located, I have 2 80mm fans behind 4 of the drives blowing air out.