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Control whether fan is on or off
- Thread starter Stevan
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Araxie
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nope, you can only do that on selected motherboards via fan header or with a fan controller.. connected directly to molex will be always on at full blast as long as the machine is also turned on
Araxie
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it is better to have an exhaust fan rather than one intake alone... intake alone if it's true will push fresh air inside the case, you will have no circulation or flow of the air inside the case at all, warm and hot air will win over fresh and all temps will be over the place.. having a single fan as exhaust even if there's no intake will cause negative airflow which will work better for overall pc cooling.
GotNoRice
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Personally I disagree.
The biggest issue with negative air pressure inside the case (more exhaust than intake) is dust. When you maintain negative pressure inside the case, that means your case will be sucking in air (and dust) from every hole on every side of the case. Also consider that power-supply fans almost exclusively exhaust hot air out of the case. With only an exhaust case fan, it's going to be fighting against your power-supply fan.
If you go with positive air pressure inside the case (more intake than exhaust), you have 100% control over exactly where air will enter your case. The random holes in the case will be exhausting air, not sucking it in. That makes it easy and practical to install dust filters, so dust never even enters your case. It's a lot easier to clean a dust filter than it is to haul your entire case outside and blow it out. Your case airflow also won't be fighting against your power-supply fan, you will be helping it.
Araxie
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yeah, that's true when you have multiple case fans and a good amount of CFM intake over exhaust.. not when we are speaking about only one fan.. OP scenario it's with a single fan
No, if your using typical tower case and intake fans have decent pressure rating (1.5mmH2O @ approx 1400rpm) exhaust fan is rarely needed. I build several computers every month and rarely use exhaust fans. Most are tower case with 2x-3x 140mm or 2x-4x 120mm front intake fans and sometimes a bottom intake as well. Link below has more details about this kind of setup.
https://hardforum.com/threads/control-whether-fan-is-on-or-off.2001608/
GotNoRice
I think you are mistaken. Most PSU fans are intakes in square side of housing and push air out the back / power lead and switch side of PSU housing
While I agree that case needs to be positive pressure, our case fans make extremely low amounts of pressure .. just enough to move air. A 1.5mm H2O pressure rating (amount of pressure fan came push into a sealed box at full speed) versus pressure of air around box is about the same difference as how much pressure air is pushing against your stomach versus on your feet standing at sea level. Yeah, that's not much difference. If that sounds wrong, look up barometric pressure at sea level vs 10 ' above sea level, subtract the difference and convert it to mm H2O. I did it several times before I believed it.
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GotNoRice
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I think you misunderstood what I said. I was talking about the direction of the airflow, not the location of the fan within the PSU. The fan may be sucking in air (from the inside of the case) into the PSU, but it's exhausting the air outside of the case through the exterior vent holes in the rear of the PSU. I believe from reading the rest of your post that we are actually in agreement.
I agree that we are not talking about high amounts of pressure, but I clean out enough old dells each week to see that even with one single exhaust fan, that small amount of negative pressure is enough to cause dust and pet hair to collect at every possible intake location around the case.
My bad. You are correct, I misunderstood what you posted.
"Airflow"through our cases is a rather misleading word. "Air movement" through our cases is probably a better way to say it. Most fans blow air in a cone shape and that air movement combined with the turbulence created by cables and pretty much everything else in our cases causes air movement in all kinds of directions. This can cause air to end up leaking into rather than out when exhaust fan/s are used. GPU fan nearest back sometimes draw air in through PCIe back slots as well.
All of the above is why I much prefer using an extra intake fan or two instead of exhaust fan/s. The extra intake airflow not only does a better job of keeping dust out but also helps push heated exhaust air on toward exhaust vents and out of case rather than mixing with and heating cool air we want going into our coolers.
I suspect you know much of this. But hopefully it will help others understand how to build a cool and quiet system.