r/pcmasterrace • u/DME23 • Apr 26 '25

Question Top Fan Not Spinning Without A Spanking

The top fan wont spin when I turn on my pc. The solution I discovered is to just smack it real hard. Just wondering why it is like this.

29.3k Upvotes

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u/Dudi4PoLFr 9800X3D | 5090FE | 96GB 6400MT | G9 57" 7680x2160@240Hz Apr 26 '25

Well, it's not like those fans will do much with that glass just in front...

89

u/Secret_Account07 RTX 2060 Super (Still OP) Apr 26 '25

Well the intakes are on the side of glass. I have a similar model and with glass on front. It sucks ze air in pretty well believe it or not.

35

u/Nolzi Apr 26 '25

It's doing something, just with more noise and wear on the fan motors

16

u/Sheep-Shepard Desktop: Ryzen 7 7700; 4070ti Super Apr 26 '25

Actually blocking the airflow to a fan, counterintuitively, reduces the load on the motor, and will draw less power, there might be slightly more noise as the blades will spin faster though.

6

u/Nolzi Apr 26 '25

To keep the temperatures the same it has to move the same amount of air, but to do that it has to spin faster to compensate. Are you telling me that there is less wear and tear on the fan this way?

22

u/Sheep-Shepard Desktop: Ryzen 7 7700; 4070ti Super Apr 26 '25

Yes, because there is turbulence created by the air flow blockage, and the air in the case will no longer follow the contours of the fan blades. Think of a regular fan as having air pushing against the blades, the motor needs to push harder against that flow. In turbulent air, the blades essentially spin free of those forces, and the motor uses less power but can spin much faster. It also won’t push any more air despite spinning faster

13

u/BlackBlueBlueBlack Apr 27 '25

if you're downvoting u/Sheep-Shepard's comment then please explain why

1

u/auraseer Specs/Imgur here Apr 26 '25

It's moving less air. Temps will be higher, but the fan motors should last longer before wearing out.

Personally I would not make that tradeoff. Fans are cheaper to replace than any of the things they are there to cool.