Question Why is my B450M-HDV R4.0 Chassis Fan Speed 100%?

watrhous

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Nov 27, 2013
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Unable to control my B450M-HDV R4.0 fan speeds even after adjusting in bios and speedfan they just blast full on.
Ryzen 3 2200g
16gb ddr4 3200 on the xmp2 profile. bios v 3.7
I have 2 x 140mm Rosewill fans on intake connected a pwm fan splitter into the 4pin chassis fan connector and 1 x 140mm out connected to the system 3 pin chassis connector.
All 3 run at 1350+ rpms while my cpu is only around 800rpm neighborhood.
How can i control the fans? Please tell me im overlooking something really simple. The bios seems to be of no effect even after adjusting it remains at 1350+ rpms. Speedfan seems to be of no effect.


EDIT: this may be unrelated but when i try to run the apps for the mobo (App shop, mobo utility, UEFI restart) they always come back with an error that this program is not for my platform ... downloaded directly from the mobo support page.
 
Last edited:

popatim

Titan
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The Chassis fan 4 pin headers usually can control 3 wire (voltage controlled) fans. Your manual doesn't clarify if it does or doesn't.

Have you go thrut he Fan-Tastic setup in your bios and tested? You might need to have that Auto-apply at startup. I haven't worked with many AsRock boards.
 

watrhous

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Nov 27, 2013
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The Chassis fan 4 pin headers usually can control 3 wire (voltage controlled) fans. Your manual doesn't clarify if it does or doesn't.

Have you go thrut he Fan-Tastic setup in your bios and tested? You might need to have that Auto-apply at startup. I haven't worked with many AsRock boards.
I was disappointed to discover that the BIOS is lacking the fan-tastic tool in it. That would certainly solve the issue. But the BIOS only has some manual settings that do not affect the fan speeds upon adjusting.
 

watrhous

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Nov 27, 2013
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Odd, the manual shows it.
yup but its not there and when i adjust the fan temp speeds in the bios it does absolutely nothing to the fan speeds. The mb software will not load either because of the error. The app store, the uefi restart button, the mb utility. I have the latest bios, i am running win10 64bit, not sure what the problem is.
 
Jan 11, 2020
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It seems that:
  • CPU and chassis 1 connectors are 4 pin and can control speed only with PWM (only for 4 pin fans)
  • chassis 2 connector is 3 pin and cannot control speed
This means, that any 3 pin fan will always spin at full speed.

It's quite sad that the manual or website don't really tell that (I wasted way too much time to find out).
 

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