should rear cooling fan blow out or suck in?

[GrefMofovich]

Hi, any case cooling experts wanna field this one? My case has no front air intake so I'm sticking the 80mm fan in the back directly below the psu. The question is, should I face the fan to suck air IN or blow it OUT? If I put it to blow in, then it blows directly onto the cpu fan. There would likely be about 6 inches of space between the comp back and the wall plus the hot air from the psu would rise so maybe that would be a nice rush of air going in from the back. Having both the psu and the fan blowing out however might cause air to be sucked in faster through the vents in the sides of the case I guess. What's better?

Thanks for any help! :t
-GM

[Johnny Fist]

I'd have to say its better to blow out in this case. If it were to blow in then it would just be circulating already hot air through the case. Getting that warm air out would be a better idea.

[Midknyte]

Agreed. Even though hot air rises, the suction of the fan would draw it back in. I would get a second fan to bring air in from the front and have the back one exhaust hot air.

[leprechaun_40]

I'd say it should exhaust ( blow out ). The reason is that it's usually mounted hi in the case and as hot air rises, this would be the best place to remove the heat from. Also, with the PSU fan exhausting right next to it, if it were set to intake, it'd be likely to get some hot air to blow in, not what you want to do.

Put a fan in front, mounted low to intake ( just don't put the machine on the floor, they make great vacuum cleaners ) and your cooling will work much more effectively.:t

[Tech^salvager]

The only time i see it suck air in is when that air is ducted to the cpu's hsf. Which alot of big name computer manufactures do these days

[bonz_dragon]

I agree that normally it should exhaust, but in my case it's also an intake along with a lower front fan. But remember this, I also have a huge 6" blow hole with an exhaust fan on the top of my case. I really needed more intake. Now I've been working on a diverter to direct the exhaust from the PSU up and away.

[Uncle Bob]

I am not an "expert," but I do know from experiance, that a fan
in the rear blowing on the CPU can disrupt the airflow from the CPU fan. Net result is hot CPU and hot air cycling inside the case.

[sm8000]

"She's gone from suck to blow!"

Sorry, blow is just a figure of speech :D

[bonz_dragon]

Originally posted by sm8000
"She's gone from suck to blow!"

Sorry, blow is just a figure of speech :D Another pointless post!

I stick by what I've said above. Watched temps after I turned it around and actually inside temps improved somewhat.
Again I have a lot of heated air moving out of the top blowhole.