Where to put a case fan?

Computer Hardware
#1

How do you decide the optimal location for a case fan? I know that this depends on various factors, and I don’t know if it really matters in my case: not overclocked, and within a good range on temp. for CPU currently (to the best of my knowledge-- am about to start digging deeper).

I have an ATX mainboard and a generic case. There’s a decent heatsink/fan unit on the CPU, and heat spreaders on the RAM modules. There are no other cooling devices on any components, but I do have an Aerocool case fan, 80mm, pretty average. (Yes, I bought it because it has pretty lights. Yes, I love things that glow in the dark.)

The two possible locations for this fan are on the back of the case, kinda level with the CPU fan, or directly across from the CPU on the broad side of the case. Is one location better for airflow than the other?

I don’t see this addressed very often…

#2

Hi,

install the fan at the rear. This will increase the existing airflow, and will also help cooling your HDD.

Michael

#3

So, is the idea is to move more air around in a case, rather than just suck hot air away from the CPU unit?
I’m in an A+ class right now, been checking the book for info, but case fans aren’t really addressed. :frowning: But I need to know these things!

Thank you, Peace and carrots!

#4

[quote=poppycat;2218131]So, is the idea is to move more air around in a case, rather than just suck hot air away from the CPU unit? [/quote]:iagree: The CPU isn’t the only heat generator in a computer. The idea is, to intake cool air from the front and to exhaust it on the (upper) rear side.

I’m in an A+ class right now, been checking the book for info, but case fans aren’t really addressed. :frowning: But I need to know these things!
ATX specs should be available on the internet.

Michael

#5

General rule:

Rear and top extract, front and side intake.

Where there is a fan postion on the rear, close to the PSU, fitting a fan there helps by extracting CPU exaust instead of warming the PSU up with it.

A fan placed to serve the HD bays is pretty specific to cooling those, and generally helps as an intake.

One reason for intake fans has more or less gone, the old ever-open floppy slot, though a decent balance of intake fans does help to avoid fluff ingestion through connector holes.

#6

lol, i like ‘fluff ingestion’. i think my cats are actually trying to feed my computer some extra fluff. nom nom nom.
Front-panel ventilation seems to be lacking on a lot of lower-end cases.

I forgot to add this to the original post: I have this tube (?) that screws against the side vent, as if to funnel the output from the CPU fan. I never noticed a lot of output coming from it, so I took it off, thinking that it kinda blocks up a lot of the case and maybe hinders airflow more than it helps vent anything. erm, good/bad/inconsequential?

Thank you again for your help.

#7

[quote=poppycat;2220072]I have this tube (?) that screws against the side vent, [/quote]I removed that tube and closed the resulting hole in the side wall of my case. HDD temps went significantly lower.
Might not be that good if a Intel PIV or PIV Celeron type heat generator is installed :smiley:

Michael

#8

I think the approved Intel layout has a chimney attached to the CPU heatsink, drawing air in through the side panel vent.

How the case fan layout works, also depends to a degree on how the CPU heatsink fan is aligned, taking the mini tower as an example, the HSF may be:

  1. Drawing from the side - ideal for side ducts or side fan assist.
  2. Bottom to top - best for extraction help from a big fan PSU, ok for rear extract fan assist.
  3. Front to back - best for rear extraction fan assist
#9

There is no perfect layout as cases very so much, and some cheaper cases don’t really pay attention to good air flow. Sometimes its just a little trial and error to see what gives the best temperatures. As others have said, top and back are most often best as exhaust. I have heard of side fans working best as intake or output depending on the computer (See which improves your temps).

Are you using the pre existing holes in your case or cutting holes for new fans? You want all you rear and top factory fan mounts filled with fans. If say for instance, you have 2 rear fan mounts but only 1 fan, it takes a lot less pressure for the fan to draw air in an empty hole and right back out the other with the fan, than it does to draw air through the entire case and through vents etc. If you cannot fill all the fan mounts, block the unused exhaust ones on the back/top as you don’t want them to inadvertently become an intake (mounting what fans you do have in the highest location). Fans are not that expensive if you get them on sale. I would strongly suggest filling all exhaust holes with fans.

Check your hard drive temps through software, or just run/use the computer for a while, then take the side off and see if they are hot. If they are a little warm, fine. If they are hot to the touch, I would try to improve cooling. If you have hard drive cage fan mounts, use them. If not, look where you have vents, and selectively, partially block them to create negative pleasure to draw air over your hard drives). I other words, if you have vents in the bottom floor of your computer, you could block them across the middle but leave them open at the front and back (it really depends on where they are located and how big they are). That way you still get air flow through the vent, but it is reduced, causing negative pressure (a vacuum), that will draw air in from other spots like the hard drives.

#10

Sorry for the delay in responding; I move back and forth between two places each week and I only get to fool with my desktop four days/week.

Anyway, my setup is an Athlon 64 X2 with a big fat AMD fan/sink on top. That draws heat up off the CPU and blows it toward the broad side of the case (the usual for an ATX/midtower setup). There is one fan mount on the back (where I put the fan) and one place on the side (roughly across from the CPU, previously had the funnel). I had, for the sake of 'sperimenting, put the fan on the side and the output was barely noticeable. So I moved it to the back and now I have a nice breeze.

The only other ventilation in the exterior of the case are four quarter-sized, mesh holes in the front panel, at the very bottom. There’s a bay where I took out a CD drive, which I covered with a panel from another computer and taped it in place (not my favorite hack), but I was thinking of getting some screen and making a vent. This would sit below the DVD drive and above a second hard drive I added.

I guess the thing to do is move items and record temps, find the sweet spot.

#11

You can try both and see what you get (you can also try reversing the fan to change direction of airflow), but I’m guessing you will get the best results with it exhausting air out the rear. You never know though. I have actually heard of someone with a case that for some reason worked better with reverse air flow (rear fans blowing in, front fans blowing out). I think there was a reason for it though (the computer was in a location where air exhaust out the back got trapped in a cabinet or something like that (and caused a heat buildup around the computer). I cannot recall for sure. It was just a thread I read some time ago on an overclockers forum.

#12

Rather than start a new post, I’ll ask here. I also have some questions about cooling.

My case has the following fan ports.

1 - 80mm on top (I can drill more holes and make it a 120mm)

2 - 80mm on side panel

1 - 120mm on side panel

2 - 80mm on front panel

1 - 80/120mm on rear

Currently I have a 120mm on the rear and 2 silent-x 80mm on the side panel.

What would be the best fan setup for the side panel and top
(Top = air out or air in?)
Side panel
(Air in or out?)

If I have to add fans, what are good that won’t be loud but offer good air flow?

#13

Top - Exhaust - 120mm
Rear - Exhaust - 120mm
Side - Intake - 120mm
Front - Intake - (2) 80mm

120mm fans will be much quieter than 80mm.

:cool::cool:

#14

[QUOTE=platinumsword;2225377]Top - Exhaust - 120mm
Rear - Exhaust - 120mm
Side - Intake - 120mm
Front - Intake - (2) 80mm

120mm fans will be much quieter than 80mm.

:cool::cool:[/QUOTE]

So, just to make sure I understand you right,

On the side panel, I should take away the 2 80mm’s and just add a 120mm?

On the top, If I exhaust, won’t that pull air away from the CPU fan that the CPU fan is trying to apply to the heatsink?

#15

[quote=axlman;2225403]So, just to make sure I understand you right,

On the side panel, I should take away the 2 80mm’s and just add a 120mm?

On the top, If I exhaust, won’t that pull air away from the CPU fan that the CPU fan is trying to apply to the heatsink?[/quote]

120mm cooling fans will move more volume of cooling air and at much lower noise level than a 80mm.

No, Your heat sink fan should either be blowing downward or across the cpu to the rear of the case, where the rear fan will exhaust the bulk of the heat. The top exhaust will pickup the difference.

:cool::cool: