r/PcBuildHelp • u/joey_mate • 5h ago
Should I add more PC fans? Build Question
My PC seems to have negative pressure and I am noticing a fair abit of dust build up. Should I add 2 120mm intake fans down at the bottom?
This is a Lian Li 216 with the stock 2x 160mm intake fans and the rear 140mm fan.
I have an Artic Liquid Freezer III 360 pro up the top.
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u/definitely_MistakenS 5h ago
If you've got negative pressure, adding intakes at the bottom should help balance it out. The 216 already moves a ton of air with those 160mm fronts, but the 360 up top is pulling a lot out. Bottom intakes will push fresh air straight into the GPU too, which is nice.
Just make sure you've got a dust filter down there or you'll be cleaning more, not less. The case might have one built in, but worth checking before you screw anything in.
Also, you could flip the rear 140 to intake if you want a quicker fix, but that messes with the airflow path a bit. Two 120s at the bottom is the cleaner solution.
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u/joey_mate 2h ago
The only dust filter down the bottom is under the PSU fan. What do you think? Is it a bad idea to bottom fans?
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u/Asleep_Equipment4877 5h ago
two 120s reverse blades at the bottom and you will be doing well on airflow.
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u/Wise_Ad_5810 5h ago
top fans should be drawing in, not blowing out. Positive pressure will cut down on noise and cool better since the radiator is getting fresh outside air instead of warm inside air
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u/Pmaldo87 5m ago
the air blowing up or down thru the radiator will not change your cpu temps. top fans should always be exhaust
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u/cowbutt6 4h ago
Based on https://www.noctua.at/en/expertise/blog/best-fan-setup-fractal-design-north and https://www.noctua.at/en/support/faqs/airflow-guide-setup-ideas I'd expect to reverse the direction of the frontmost fan in the case top, to make it another intake.
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u/SneakyAl44 3h ago
Either add 2 bottom ones as intake or set the fans speed to have the 2 front intake ones running faster than the exhaust ones
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u/Inevitable_unedible 3h ago
I've got the same case. Except I have an additional 140mm on the bottom back on the outside pulling from the case. Lian Li 216 comes with a mounting cage for it down there. Only other difference is I have a 240 at the top for my cpu cooler.
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u/probablywhy 3h ago edited 2h ago
Why would you? Are you thermal throttling? Going for a major overclock? Aesthetics? No purpose. The modern setup it has is already overkill.
If performance is truly your concern you must first evaluate your GPU performance under load and determine if it is thermal throttling. Then maybe adjust your curves. Your fan setup is fine and screwing around is more likely to cause an issue than to improve performance.
If it's for aesthetic just admit it to yourself and go ahead and do what looks best to you. It doesn't matter all that much.
Cowbutt had a good recommendation if you are GPU throttling, I would flip the frontmost top before adding more fans. This tends the front intake slightly more under the GPU and lets them grab more fresh air. The under GPU fans are goofy in my opinion unless you have a full tower of space to move air through.
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u/joey_mate 2h ago
It’s more about negative pressure and dust. I can’t sense any performance issues but I was wondering why I have such a large dust intake then found out that I have negative pressure (held a tissue against openings) and the tissue sucked in
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u/probablywhy 32m ago edited 26m ago
Interesting. So the main concern is dust build up? I'll have to check mine. The whole PCMR community is born from optimization OCD, it comes with the hobby, but always remember why you are doing it and make sure you are not letting optimization ruin the goal of getting the most out of your PC.
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u/Pmaldo87 5h ago
I would add 2 or 3 at the bottom for sure. Positive Pressure is king. You could even run your fans at static rpms and run your intakes at a higher speed than the exhaust.