Exhaust Fan
- Thread starter Loxa
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Depends on fan ratio if you have the same amount of intake to exhust then slower exhaust fans would give a slightly positive airflow.
A setup with 4 intake and 1 exhaust & a setup with 6 intake 1 exhaust.
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You would get better airflow with another exhaust in each but if you cant then increasing the exhaust speed can only help.
Noise is a factor increasing fan speed.
Ok interesting, always wondered about exhaust rpm. Something that seems overlooked a lot.
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Maybe because most people would have another exhaust fan or an aio cooler exhausting air.
Sure you want postive air pressure but also movement of air in and out the case so the faster you can expell hot air the cooler the system.
4:1 and 5:1 fan ratio.
How many vents does each case have?
Case need at least matching number of intake to exhaust vents. I prefer more out, usually with no exhaust fans at all .. I just let the intakes push air all the way through. I build several systems a month and haven't used an exhaust fan in so long I can't remember when last one was.
How many vents does each case have?
Case need at least matching number of intake to exhaust vents. I prefer more out, usually with no exhaust fans at all .. I just let the intakes push air all the way through. I build several systems a month and haven't used an exhaust fan in so long I can't remember when last one was.
Usually intake's performance would be affected by filters + any grill or other obstacle on the way. Exhaust fans normally only "fighting" against grill/mesh.
So if you have the same number of intake as exhaust, pretty much you would have negative pressure.
Here with 6 intakes (in reality 12, as they're push/pull) and 4 exhaust (3 of them push against another rad), at the same RPM, the airflow is decent and I haven't noticed any dead spot. Filter only on bottom.
Before the O11 LX, with the O11 Air, I was using 9 intake and 4 exhaust (3 exhaust pushing against the AIO rad), and wasn't an issue either.
As long you don't go all intake or all exhaust, where the air would only (mainly) enter or exit from rear mesh and tiny gaps, should be fine. Going all intake or exhaust, unless on very specific scenarios would create dead spots or keep the air stagnated for too long inside the case.
You should always aim to have an airflow path where the air enters and exit the case as quick as possible.
Regular layout cases usually bottom/front/side as intake and top/rear as exhaust. Nothing to do with hot air rises, as airflow from fans would easily overcome that. Also bottom intake could help a lot the GPU temps.
So if you have the same number of intake as exhaust, pretty much you would have negative pressure.
Here with 6 intakes (in reality 12, as they're push/pull) and 4 exhaust (3 of them push against another rad), at the same RPM, the airflow is decent and I haven't noticed any dead spot. Filter only on bottom.
Before the O11 LX, with the O11 Air, I was using 9 intake and 4 exhaust (3 exhaust pushing against the AIO rad), and wasn't an issue either.
As long you don't go all intake or all exhaust, where the air would only (mainly) enter or exit from rear mesh and tiny gaps, should be fine. Going all intake or exhaust, unless on very specific scenarios would create dead spots or keep the air stagnated for too long inside the case.
You should always aim to have an airflow path where the air enters and exit the case as quick as possible.
Regular layout cases usually bottom/front/side as intake and top/rear as exhaust. Nothing to do with hot air rises, as airflow from fans would easily overcome that. Also bottom intake could help a lot the GPU temps.
Guess I should have been clearer. Very few of us have fans in all vents.
While it's true back exhaust venting doesn't have filters, punched metal vent grills are only slightly less restrictive than fancy front vent grills. Fitlers restrict flow about the same as normal vent grill so vent with filter flow about have as much as vent without filter.
While it's true back exhaust venting doesn't have filters, punched metal vent grills are only slightly less restrictive than fancy front vent grills. Fitlers restrict flow about the same as normal vent grill so vent with filter flow about have as much as vent without filter.
Only if the filter is the only thing affecting the intake. Usually there's more to it, like the O11. Air would have the same obstacles as the exhaust, plus filter.
And not forgetting that some fans are better at push than pulling when any obstacle is added.
I tried quite a few combinations until I got to where I'm happy. Surprisingly having the top as intake rather than exhaust worked better, perhaps due to the mesh filter. With my case and fans there is definitely a lot more restriction with the filters than without.
All Corsair ML140 fans and this gave me the coolest and quietest setup with CPU idle/normal use temp at around 35/42°C and goes up to about 55°C under load, and the case, chipset etc barely touches 40°C under heavy load. The GPU has nice airflow over it as well thank to the lower front fan.
x2 FRONT 140mm intake (metal mesh filter) - set to approx. 350rpm under normal load with fan profiles set for gradual increase
x2 TOP 140mm intake (metal mesh filter) - set to approx. 350rpm under normal load with fan profiles set for gradual increase
x1 REAR 140mm exhaust (non filtered) - set to approx. 550rpm with fan profiles set for gradual increase
There's also a 140mm fan pushing air through the CPU heatsink to the rear exhaust which runs at about 550rpm under normal conditions.
All Corsair ML140 fans and this gave me the coolest and quietest setup with CPU idle/normal use temp at around 35/42°C and goes up to about 55°C under load, and the case, chipset etc barely touches 40°C under heavy load. The GPU has nice airflow over it as well thank to the lower front fan.
x2 FRONT 140mm intake (metal mesh filter) - set to approx. 350rpm under normal load with fan profiles set for gradual increase
x2 TOP 140mm intake (metal mesh filter) - set to approx. 350rpm under normal load with fan profiles set for gradual increase
x1 REAR 140mm exhaust (non filtered) - set to approx. 550rpm with fan profiles set for gradual increase
There's also a 140mm fan pushing air through the CPU heatsink to the rear exhaust which runs at about 550rpm under normal conditions.
All true, but every grill air goes through is additional resisance to the airflow. I think you missunderstood what I said, I said "Filters restrict flow about the same as normal vent grill so vent with filter flow about have (sp should be half) as much as vent without filter." What I said in post you quoted is that filter and grill flow about half as much as just a grill. I said front grill and filter
First we have a grill on case, than a filter often on front of another grill before air even reaches fan.
Then air goes on through case with other airflow resistance (even a small cable in airflow creates turbulence thus resistance to airflow all the way to exhaust grill
Then throug resistance of exhaust grill on it's way out of case.
All these different sources of resistance diminish case airflow
The more exhaust vent area we have the lower the resistance is to the air flowing through it.
So if we have
3x 140mm intakes filling from of case
1x bottom vent
2x top vents
1x back vent plus whatever other venting / openings there are in back
we end up with 3x intake vents wiht fans and 4x exhaust vents with our without fans. I've found with that kind of setup if all openings in front half of case are blocked of so air front intake push into case can't leak our/go back in front of intake fans the air fans push into case flow very nicely on through case. I also remove all PCIe back slot covers to increase rear vent area around GPU for better front to back flow, thus lower fan speed and less noise.1x bottom vent
2x top vents
1x back vent plus whatever other venting / openings there are in back
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That's interesting, I might try that as my 1660 Super can get a little loud and as I'm running pretty high positive pressure then I'm hoping they will act as a nice set of passive exhaust vents?
Many builds have way too many fans. The smoother the airflow the less turbulence there is, and the less turbulence the less heated exhaust air mixing into cool airflow through case.
Top intake push air at right angles to front intakes.
Top intake and exhaust tend to create a circle of airflow. Higher pressure air out of fan is drawn to lower pressure air being drawn into other fan.
Bottom intake sometimes helps as it flows toward GPU.
You might find link below interesting. It's a short guide about how airflow works and how to optimize case airflow:
https://forums.overclockers.co.uk/t...-i-put-my-temp-sensor.18564223/#post-26159770
Thanks for the info, I'll have a read.
Changed my fan setup from a 6 intake / 1 exhaust to 6 intake / 4 exhaust and my cpu temp dropped 15c and motherboard temps/m.2 dropped 30c.
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Quick follow up, temps have been all good since the change but was just wondering if having faster intake than exhaust is better or all runnning the same speed is fine. If it will make no difference to thermals then i will lower the fan speed slighty (from 50% to 40%) to lower noise levels.
6 intake / 4 exhaust
6 intake / 4 exhaust