Intake or Exhaust fans?

[xRorz]

My only exhaust fan broke on my yesterday and was wondering whether or not I should change my setup and have 2 intake fans instead? (My case is awful and as far as I know, only has 2 slots for fans.) I had an intake which was 80mm and an exhaust which was 120mm. I was wondering whether or not I should instead just have two intakes as the one I already have is tiny? Or an 80mm in and 120 out? Or other way round? I don't know, which is why I need advice.

And no, a new case isn't an option lol.

 

[geofelt]

What is your case?
What do you have inside?

If possible, have both fans working as either intake or exhaust. If possible make the stronger pair as intakes.

 

[xRorz]

What is your case?
What do you have inside?

If possible, have both fans working as either intake or exhaust. If possible make the stronger pair as intakes.

I have no idea what case I have. It's unbranded and pretty small.

(I assume you're asking specs) i7-4770 and a GTX 770

Would it be ok to have the 120mm at the back as intake and the 80mm on the side exhaust?

 

[Dugimodo]

TL😀R - If you only have one fan make it a rear exhaust.

In general Exhaust fans work better. An Exhaust Fan near the top where the hot air accumulates removes heat from the case. If you only have intakes you are not controlling what air leaves the case and from where and will only cool things that are right in front of the fan.

An intake only setup can work very well if designed right but few cases are designed well enough for that and it's safer to just stick with an exhaust fan. Hot air will always find it's way out of vents near the top but it may not do so fast enough and may accumulate in "hotspots" if you don't exhaust it.

As an example I stress tested my CPU and graphics card with the front intake fan on and off, it made no difference at all to the results but the hard drives near the intake did get a little warmer with it off. I tried again without the rear exhaust fan and both test result went up significantly. The hard drives also got hotter than any of the other tests even though the intake was still on and blowing air towards them. This was years ago with a core 2 Duo in a very basic case but the design hasn't changed that much.

Also worth noting if you have negative pressure which is the norm (Blowing more air out than sucking in) Air will find it's way into the case from every possible direction and you need to clean the dust out reasonably often to stop it accumulating.

If you have positive pressure (Blowing more air in than sucking out) and filter the intake fans the inside of the case stays very clean and you only need to clean the filters from time to time. This is difficult to achieve in practice though and filters seriously reduce the airflow and cooling efficiency of the fans.

Think about this, if you have a fan sucking cool air in the front and a fan blowing hot air out the back all the front fan does is help to control where the cool air comes from and what direction it moves, but if you remove it exactly the same amount of hot air is still leaving the case from the same place.

 

[xRorz]

TL😀R - If you only have one fan make it a rear exhaust.

In general Exhaust fans work better. An Exhaust Fan near the top where the hot air accumulates removes heat from the case. If you only have intakes you are not controlling what air leaves the case and from where and will only cool things that are right in front of the fan.

An intake only setup can work very well if designed right but few cases are designed well enough for that and it's safer to just stick with an exhaust fan. Hot air will always find it's way out of vents near the top but it may not do so fast enough and may accumulate in "hotspots" if you don't exhaust it.

As an example I stress tested my CPU and graphics card with the front intake fan on and off, it made no difference at all to the results but the hard drives near the intake did get a little warmer with it off. I tried again without the rear exhaust fan and both test result went up significantly. The hard drives also got hotter than any of the other tests even though the intake was still on and blowing air towards them. This was years ago with a core 2 Duo in a very basic case but the design hasn't changed that much.

Also worth noting if you have negative pressure which is the norm (Blowing more air out than sucking in) Air will find it's way into the case from every possible direction and you need to clean the dust out reasonably often to stop it accumulating.

If you have positive pressure (Blowing more air in than sucking out) and filter the intake fans the inside of the case stays very clean and you only need to clean the filters from time to time. This is difficult to achieve in practice though and filters seriously reduce the airflow and cooling efficiency of the fans.

Think about this, if you have a fan sucking cool air in the front and a fan blowing hot air out the back all the front fan does is help to control where the cool air comes from and what direction it moves, but if you remove it exactly the same amount of hot air is still leaving the case from the same place.

Thanks for the detailed reply.

I guess I'll have the 120mm as exhaust at the back and the small 80mm at the side as an intake. Thanks.