[SOLVED] Case fans placement

[Emylian91]

How is it recommended that one should position the fans if the case has 2 top fans and a rear fan ? Should the upper fans be for exhaust and the rear one for intake ? My friend has them other way around and he says the case side panel gets hot.

 

[Phaaze88]

Full PC specs? Include cpu cooler, case model as well please.

 

[Emylian91]

-CPU Ryzen 5 2600
-GPU Geforce RTX 2060 OC 6GB
-PSU Corsair CV650 80 Plus Bronze 650W
-Case Floston HERO RGB STRIP TG
-16 GB ram 3200 frequency
-Stock CPU cooler
-Added 2 RGB Floston HALO RGB LED on the top of the case
Pics:

https://imgur.com/6hRGkhV

View: https://imgur.com/6hRGkhV

https://imgur.com/8lILKkX

View: https://imgur.com/8lILKkX

 

[Phaaze88]

What kind of temps do the cpu and gpu see?

I take it the front fans are also intake? I can't see them.

By the way, glass is an insulator of heat; it does not travel through as easily compared to a solid metal panel.

 

[Emylian91]

What kind of temps do the cpu and gpu see?

I take it the front fans are also intake? I can't see them.

By the way, glass is an insulator of heat; it does not travel through as easily compared to a solid metal panel.

There are no front fans. As I previously sayd, 2 top and 1 rear. I will have to ask him for temps.

 

[Karadjgne]

If keeping just those 3 fans, then make them all exhaust. You'll have plenty of suction to draw air from the front.

A gpu pulls air into its fans, so the air comes from below. It exhausts out the side, nearest the glass. If you run top as intakes, it forces that heat right back down onto the gpu area, you end up with the gpu cooking in its own waste. By running top fans as exhaust, that'll help create an airflow path from low to high, so now the gpu exhaust has somewhere to go. The side panel may still get warm, no choice there with a high power gpu blowing on it, but at least it won't be added to constantly.

Bonus being the RGB from the fans is all inside the case, looks better.

 

[SkyNetRising]

There are no front fans. As I previously sayd, 2 top and 1 rear.

Why not?
Move those 2 from top to front intake position.

 

[Karadjgne]

I forsee the same affect with that case as with the nzxt H510, front fans doing next to nothing for airflow, and actually making gpu temps worse.

 

[jesse13williamson]

If keeping just those 3 fans, then make them all exhaust. You'll have plenty of suction to draw air from the front.

Hi. I don't disagree with you at all, but I was just wondering something regarding this advice. I always heard that positive case pressure is preferable to negative in terms of both dust and airflow. If enough air could be drawn through the front to sufficiently cool the case through pressure alone, then wouldn't it be better to mount the two fans as intakes on the front? That way, it would at least equalise case pressure, and the hot air would still be able to rise through the empty fan mounts on the top of the case, as well as be pushed through the exhaust.

Sorry if I came off as argumentative at all, I don't mean to. I'm still trying to wrap my head around best airflow practice a bit. Thanks!

 

[Karadjgne]

Not argumentative at all. There's a fine line between positive and negative, and fan count is only a partial player. It's mostly derived from the amount of pull the rear exhaust has.

Fans work by a blade moving through air. Because of the pitch of the blade, this leaves a low pressure area behind it, the byproduct being pressurized air forced away from the front side. So the faster the blade spins, the stronger the low pressure area is.

But, that affects the whole area surrounding the fan, not just a cone like the forced air. As a consequence, that low pressure will attract air from the nearest strongest source, and in the case of a rear exhaust that happens to be the 14.7lbs in² that's coming through the top fan vent hole. To overcome that and have a positive system takes a lot more than what front fans can supply, especially at idle speeds, so you'll find almost all cases with top vents run negative at idle. Having an exhaust at the top rear makes that low pressure area stronger, increasing the pull towards the front of the case.

This works for the gpu too. The gpu draws air in from underneath, creating a low pressure area below it, nearest the fans. Normally this is fed by the front fans with decent static pressure forcing the cfm across that relatively small distance in a direct shot. But many newer closed front designed cases have such lousy air draw characteristics that even with high speed fans, they are not getting enough air fed into them, like spinning in a vacuum doing next to nothing. So only a little air makes it to the gpu. Without that fed air, the gpu will pull air from the pcie slots next to it, and that air is generally cooler than the air from the fans pushing case temp air around. In cases like the nzxt H510, it's been tested and proven the gpu runs cooler without front intake fans, relying solely on what it pulls from the rear.

Having nothing but negative pressure might make for a little more dust, but at low movement rates the air will get pulled through the easiest source first. The big gaping holes where the front intakes are usually, covered with a dust filter.

It's not a new concept, all the original pc cases had nothing but a rear exhaust. The difference now is a far more efficient cpu cooler and a gpu that naturally wants its exhaust to rise.

One of the best airflow cases around is the fractal design meshify C, 3x intakes and 1x measly exhaust. Runs a positive system almost all the time, the 3x fans well over compensating for any distance. As long as the silencer tops are in place, creating basically a tunnel. Remove just one cap and airflow goes in the toilet as the rear now has fresh access directly above, the intakes not having enough.

You can test it out, 3x exhausts vrs 1 exhaust and 2x intakes, but I'm betting you'll get better temps with a negative system.

 

[Phaaze88]

Negative pressure tends to work better in chassis with poor front intakes - the closed off, or near closed off front panels.

 

[jesse13williamson]

Not argumentative at all. There's a fine line between positive and negative, and fan count is only a partial player. It's mostly derived from the amount of pull the rear exhaust has.

Fans work by a blade moving through air. Because of the pitch of the blade, this leaves a low pressure area behind it, the byproduct being pressurized air forced away from the front side. So the faster the blade spins, the stronger the low pressure area is.

But, that affects the whole area surrounding the fan, not just a cone like the forced air. As a consequence, that low pressure will attract air from the nearest strongest source, and in the case of a rear exhaust that happens to be the 14.7lbs in² that's coming through the top fan vent hole. To overcome that and have a positive system takes a lot more than what front fans can supply, especially at idle speeds, so you'll find almost all cases with top vents run negative at idle. Having an exhaust at the top rear makes that low pressure area stronger, increasing the pull towards the front of the case.

This works for the gpu too. The gpu draws air in from underneath, creating a low pressure area below it, nearest the fans. Normally this is fed by the front fans with decent static pressure forcing the cfm across that relatively small distance in a direct shot. But many newer closed front designed cases have such lousy air draw characteristics that even with high speed fans, they are not getting enough air fed into them, like spinning in a vacuum doing next to nothing. So only a little air makes it to the gpu. Without that fed air, the gpu will pull air from the pcie slots next to it, and that air is generally cooler than the air from the fans pushing case temp air around. In cases like the nzxt H510, it's been tested and proven the gpu runs cooler without front intake fans, relying solely on what it pulls from the rear.

Having nothing but negative pressure might make for a little more dust, but at low movement rates the air will get pulled through the easiest source first. The big gaping holes where the front intakes are usually, covered with a dust filter.

It's not a new concept, all the original pc cases had nothing but a rear exhaust. The difference now is a far more efficient cpu cooler and a gpu that naturally wants its exhaust to rise.

One of the best airflow cases around is the fractal design meshify C, 3x intakes and 1x measly exhaust. Runs a positive system almost all the time, the 3x fans well over compensating for any distance. As long as the silencer tops are in place, creating basically a tunnel. Remove just one cap and airflow goes in the toilet as the rear now has fresh access directly above, the intakes not having enough.

You can test it out, 3x exhausts vrs 1 exhaust and 2x intakes, but I'm betting you'll get better temps with a negative system.

Ahh I see. Thanks a lot for the great reply!

 

[Karadjgne]

Sorry it was so long winded lol. But yes, generally front intake, rear exhaust is best, but that's not always the case, a lot depends on the actual airflow characteristics of the case in question. As much as yours looks to be modeled like the H510, I'd be very inclined to full exhausts, but it might do just as good with 1 intake high or low or 2 intakes in front. You'd be the best judge for that, just move the fans around and see what works better for cpu and gpu.