Member Avatar for rajhoq12

i have a old computer here prcessor fan is not running well. after 12/15 mins it's droped

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A focused troubleshooting note for a CPU fan that runs briefly then "drops" after ~12–15 minutes. The symptom narrows the cause to three broad areas: mechanical (bearings or hub overheating), electrical (connector/wiring or motherboard fan header), or control (PWM/BIOS behaviour). Several posters here already suggested cleaning, testing the fan on another board and checking the header; the steps below turn those ideas into a clear diagnostic flow and safe repair options.

  • Visual/quick checks: inspect the fan plug and header for broken wires, bent pins, corrosion or melted plastic. While the system is running, gently wiggle the cable; intermittent contact that changes fan behaviour indicates a wiring/connector fault.
  • Direct-power test: power the fan from a 12 V PSU source (Molex-to-fan adapter). If the fan runs continuously when fed direct 12 V, the fan motor is OK and the motherboard/header/control is the likely problem. If it still stops, the fan itself is failing.
  • Header/voltage test: with a multimeter set to DC volts (carefully, avoid shorting pins), check the header output. For 3-pin headers expect steady ~12 V at full speed; 4-pin PWM headers may show pulses or a 5 V PWM control line, so set BIOS to full-speed/disable PWM for a simpler measurement. Abnormal or absent voltage points to the board.
  • Cross-check with a known-good fan: plugging a working fan into the CPU header tells whether the header is healthy.

Mechanical repair note: if the fan is a sleeve-bearing type, a careful single-drop lubrication can temporarily restore life — remove the hub cap, clean old gunk, add one drop of light sewing-machine/synthetic oil, spin to distribute, then reassemble. Do not use penetrating sprays like WD-40; ball-bearing or sealed fans rarely benefit and lubrication is only a stopgap.

Laptop fans and integrated assemblies are harder to bench-test and often require disassembly or replacement. If testing isolates a faulty fan, replacement is the long-term, safe solution; if the header is at fault, consider an alternate header, BIOS fan-curve changes, or a powered fan adapter. This sequence keeps troubleshooting logical and limits risk to the CPU and board.

Recommended Answers

All 10 Replies

Member Avatar for Rik_

Put a new one on it then!!!

Member Avatar for benmar

try to clean the dust,, or put some oil on it...make the motor easy to span...

Member Avatar for Hazuan Nazri

are you using notebook or Desktop?

Member Avatar for sumanrox

If you use desktop computer then you need clean the dust of the fan. But the best option is buy a new fan.

Member Avatar for ananthapriya

yeah i am alos having this same problem but my problem is different one. Would anyone know why a CPU fan would stop running. I removed the fan from the heat sink and tested it on a different motherboard. It worked fine. I suspect my current motherboard and maybe some BIOS settings may be disable but I don't know where and what to look for next.

Member Avatar for Wil 0' Wisp

Answer to first problem. Buy a new fan and soon! it sounds suspiciously like you are cooking the Processor! And suck the dust out of the system. Power the system off and use a vaccum cleaner/airduster areosol.

Answer to Hijack above,It's the pins on the board that have failed look for the pin outs marked sysfan on the board, you may find these are still operational. The problem you may encounter from here, is that some systems may not boot as the system cannot detect the fan.

Member Avatar for mayaestat

Buy a new fan I thick Noctua is the best manufacture of cpu cooling fans ..

Member Avatar for lukaterra

Hi!
I advise you first clean your radiator and fan, and change thermal compound. It can help you, because your PC allready worked well with this fan and problem appeared recently

Member Avatar for pintukennady31

change the fan oterwise it will harm your computer.and for best cpu fan google it .you will find the best one.

Member Avatar for MatthewWri

Open your Fan and clear the dust and put it back in and try... if same issue occure then you need to replace your fan.

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