Case - Top Fan / Vents? (Why do most boxes have a single exhaust out the back?)

DarkSideA8

Limp Gawd
Joined
Apr 13, 2005
Messages
384
It's time to replace my aging and decrepit Corsair 600t. I've been looking at cases - and have a question.

My 600t has a massive front fan, a rear exhaust fan and a large fan pushing air straight out the top. Most of the cases I've looked at don't have this top fan. I see multiple small fans front and a single exhaust fan rear offered most often.

Is there a reason for this?

It seems like a natural thing, given the way hot air moves (and how chimneys work) to vent hot air up.

Can someone explain why I'm not seeing more fans in the top of the cases currently available?
 

SticKx911

2[H]4U
Joined
Mar 14, 2004
Messages
2,430
Looks would be my guess. For a clean smooth top. Typically you want to aim for positive pressure to reduce dust building up, and filtering the incoming air helps even more. I'd guess most of those cases that are 2 to 1 have a washable filter on the 2.
 

Nobu

Supreme [H]ardness
Joined
Jun 7, 2007
Messages
4,777
One exhaust is usually enough, nothing else would otherwise occupy the rear of the case, and the hot air will rise to the top, then get swept up by the rear exhaust.

On cases designed for better airflow, they'll usually have two or three in the front, one or two in the bottom, and then one in the rear and 1-3 in the top (the number in the bottom and top mostly determined by fan size and psu placement). This arrangement allows more than enough fans for intake, and enough for exhaust that you won't have a hotbox (as long as you aren't way unbalanced, anyway).

In either case, you need at least one exhaust fan. I found that out the hard way in my antek itx case. I had three fans pushing air in on one side, straight through the case to vents of equal size on the other side. Only other fan was the CPU fan. The difference between that and having them exhaust was 10°c in favor of exhaust under load, although I'm sure having a more balanced setup wouldn't hurt.
 

THUMPer

2[H]4U
Joined
May 6, 2008
Messages
3,440

Attachments

  • IMG_20200811_105924.jpg
    IMG_20200811_105924.jpg
    425.1 KB · Views: 0

Denpepe

[H]ard|Gawd
Joined
Oct 26, 2015
Messages
1,699
One reason could be that you need to put the fans and radiator of your AIO somewhere in case you go that route, and ofc for them to be able to sell it cheaper
 

TheSlySyl

Gawd
Joined
May 30, 2018
Messages
602
You're probably mostly looking at cheaper cases. (Or glass cases?) Once you get to the $100-$200 range they usually have room at the top for large radiators. My older Define R5 had room up top and in front for a 360 rad, and the Define 7 is even more ridiculous.

1600190965063.png
 

Ready4Dis

2[H]4U
Joined
Nov 4, 2015
Messages
2,375
Yeah, I've seen plenty of cases with the top fan, not sure which ones you're looking at. Got my son an NZXT h510, not the best air-flow case, but it does have front, back and top fans and it was like a $70 case. Even his old case which was like a $40 shipped cheapy had a spot for a top mount 240mm rad.
 

Guarana [BAWLS]

[H]ard|Gawd
Joined
Oct 3, 2001
Messages
1,881
It's time to replace my aging and decrepit Corsair 600t. I've been looking at cases - and have a question.

My 600t has a massive front fan, a rear exhaust fan and a large fan pushing air straight out the top. Most of the cases I've looked at don't have this top fan. I see multiple small fans front and a single exhaust fan rear offered most often.

Is there a reason for this?

It seems like a natural thing, given the way hot air moves (and how chimneys work) to vent hot air up.

Can someone explain why I'm not seeing more fans in the top of the cases currently available?

So, does heat rise? Of course it does.

But it does so very very slowly.

Creating a consistent flow of air from front to rear? Much more effective at cooling than relying on convection to move air / heat vertically.
 
Top