Fan directions

[Verified1]

I'm looking for opinions on the best way to configure my case fans. I have a microATX case with a 240mm rad in the front, there's no room to put it in the top. The diagram shows how I have it currently and how I thought it would be best. I decided to make the top fans intakes for two reasons:

-The intake at the front could potentially be kind of weak because the static pressure fans are pulling air through both the front of the case and the radiator.

-If the top fans were exhausts, it would probably cause negative pressure inside the case, which people usually say is bad.

 

There is a nice air filter on top, so dust shouldn't be a problem if the top fans are intakes. What do you all think about this?

[Electronics Wizardy]

Id go with the top to have no fans or be an exause. I think the air will just go in a loop from the top to the back, and not really be useful. If it was an exaust it should help pull air from the radiator.

 

I worry more about your gpu in all of this. How is it gonna get cooling?

[Poinkachu]

23 minutes ago, Verified1 said:

I'm looking for opinions on the best way to configure my case fans. I have a microATX case with a 240mm rad in the front, there's no room to put it in the top. The diagram shows how I have it currently and how I thought it would be best. I decided to make the top fans intakes for two reasons:

-The intake at the front could potentially be kind of weak because the static pressure fans are pulling air through both the front of the case and the radiator.

-If the top fans were exhausts, it would probably cause negative pressure inside the case, which people usually say is bad.

 

There is a nice air filter on top, so dust shouldn't be a problem if the top fans are intakes. What do you all think about this?

 

IMHO, the only downside of a negative pressure is the dust accumulation. Which is not really a problem if you periodically clean your system.

If you hardly clean your system, then dust build up doesn't really matter for you anyway.

Honestly I ran my old PC with negative pressure and sometimes even with side panel off for years, and the dust wasn't that bad. Eventhough I live in a very dusty country.

 

The way my logic sees it, the air coming from the top isn't gonna reach GPU much anyway, since it will clash with the air coming in from the front.

There's also a chance that the hot air your GPU expels gonna have a hard time reaching exhaust due to being pushed down by top intake.

 

But yep, I'm not a master at fluid dynamic, so I might be wrong.

 

Like @Electronics Wizardy said, try with no fans at all on top. Depending on your system you might not even need that much intake / exhaust.

[TPCEA]

Ignoring the errors in arrow coloration, this might help. 

The pictures clearly show that the recommendation for CPUs is front mount intake with the tubes down so that air gets trapped in the other end of the rad, vindicating the stated front mount belief. The article itself fails to state exhaust or intake for the configurations shown. 

 

The secondary recommendation is front exhausting with tubes down, which the image shows is second best at almost 3 degrees hotter.

 

Third best is top mount exhausting at 4.6 degrees hotter than #1, followed closely by front tubes up intake.

 

If you want to give the GPU better cooling, it's completely different. 

 

Results may vary depending on your setup.  I hope this helps. 

[CDR_Xavier]

If I were to say my true opinion, I would double-stack the front (have a fan both before and after the radiator), seal the top and leave the rear exhaust.  Put the fan filter on the front, if the front isn't filtered.

 

Assuming your aio is for your CPU, as long as both of your temps is ok I don't see a lot of problems. Except, since your aio may restrict flow, you should use exhausts to encourage more flow through the aio (?) or make aio the exhaust and have more intakes.

As shown in the picture, the middle two rows (where all except rear are intake/exhausts) have very high temps. This is expected as the air can only exit through the rear single fan. So you need to pick one as intake and the other as exhaust. As for which one (top, front) is in/out, and radiator where, is more of personal choice. Top exhaust does make sense (hot air rises), but top intake also make sense (cool air falls).

 

Regarding tubes up/down I think it's exaggerated, but it may make a difference on lower-quality AIOs. Tube down also encourages natural convection (hot water rises cold water sinks)

 

If your GPU is a turbine card, a positive-pressure setup like (your current one) can help a bit (maybe 5 degrees). Although on mine I have to reverse the rear fan (so it's also intaking), and tape up the drive bays at the front, leaving my GPU (and power supply) as the only two exhaust, as I don't have upper fan mounts/positions and only a 80mm frontal fan mount.

Lots of static pressure (probably 3mm H2O) inside.

[thejackalope]

I would put the AIO on top and have it exhaust, and use all the other fan positions as intakes

[Whatisthis]

2 hours ago, thejackalope said:

I would put the AIO on top and have it exhaust, and use all the other fan positions as intakes

This would be less efficient. Front mount rad pulling in cold air with back and top as exhaust will get you the best cpu temps in most cases. The air is a few degrees warmer leaving th radiator, but not enough to cook the rest of your components. 
 

If you need the best GPU temps, a side mount fan blowing toward the card will do that for you.

 

it’s all pretty academic anyway. Anywhere you install the rad it will be able to cool the cpu unless it is literally on the edge of being able to do so.

[thejackalope]

2 hours ago, Whatisthis said:

This would be less efficient. Front mount rad pulling in cold air with back and top as exhaust will get you the best cpu temps in most cases. The air is a few degrees warmer leaving th radiator, but not enough to cook the rest of your components. 
 

If you need the best GPU temps, a side mount fan blowing toward the card will do that for you.

 

it’s all pretty academic anyway. Anywhere you install the rad it will be able to cool the cpu unless it is literally on the edge of being able to do so.

It's not cooking your components but it is contributing to higher temperature in the case. If the AIO can still do a great job cooling the CPU with slightly warmer air, it makes more sense to not dump that air into the case