are you sure it is the rear chassis fan changing speed? that fan plugs into 3 pin fan header (fan_sys on motherboard) and is at constant speed. The system only adjusts cpu heatsink fan automatically (PWM) depends on cpu temp. cpu fan plugs into Dell proprietary 5 pin header. If fan is loud all the time, check cpu temp using HWMonitor to see if it is too high. If yes it suggests heatsink is not dissipating heat appropriately.
Yeah, i did a system diagnostics and the it is the rear fan that is around 2200RPM. It can go up in RPM but doesn't slow down after. The CPU is an i3 4170 so im not sure if that has anything to do with it. All the temps seem normal in HWMonitor.
The rear fan is temp. controlled, otherwise, it would be at full blast all of the time. Since temps show as normal, that doesn't suggest it could be a heat sensor. But the fan does report back to the MB and may be due for replacement.
speedstep
9 Legend
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47K Posts
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November 15th, 2020 03:00
There is no user fan control on Optiplex models.
redxps630
9 Legend
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November 15th, 2020 08:00
are you sure it is the rear chassis fan changing speed? that fan plugs into 3 pin fan header (fan_sys on motherboard) and is at constant speed. The system only adjusts cpu heatsink fan automatically (PWM) depends on cpu temp. cpu fan plugs into Dell proprietary 5 pin header. If fan is loud all the time, check cpu temp using HWMonitor to see if it is too high. If yes it suggests heatsink is not dissipating heat appropriately.
bradthetechnut
7 Technologist
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November 15th, 2020 17:00
Adding to what redxps630 said, make sure the system is clean if not already.
ssssssssssssss
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November 16th, 2020 13:00
Yeah, i did a system diagnostics and the it is the rear fan that is around 2200RPM. It can go up in RPM but doesn't slow down after. The CPU is an i3 4170 so im not sure if that has anything to do with it. All the temps seem normal in HWMonitor.
bradthetechnut
7 Technologist
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9.4K Posts
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November 19th, 2020 18:00
The rear fan is temp. controlled, otherwise, it would be at full blast all of the time. Since temps show as normal, that doesn't suggest it could be a heat sensor. But the fan does report back to the MB and may be due for replacement.