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08-21-2018 06:37 PM
The case fan runs too fast continuously. It runs at about step 5 of 8 steps in the bios settings under THERMAL>idle fan speed. In bios I can speed the fan up from 5-8 but cannot slow it below step 5. The fan used to be whisper quiet, now it can be heard from 20-30 feet away.
The first time the fan ran too fast cleaning the nVidia Quadro FX1700 graphics card fan solved the problem for about a year and then it happened again. When a repeated cleaning failed to restore the fan to normal operation I replaced the graphics card with a used identical card.
Upon booting up after the card swap the computer fan ran normally. I let the computer run with the side cover removed for a hour. When I started to replace the side cover the fan suddenly runs at full speed; take the side cover off and the fan slowly returns to normal speed. I wiggle the front panel on/off wires and the fan immediately runs full speed then gradually slows to normal. I repeat the wiggle test a couple more times with same results. On the last wiggle test the fan never slowed down. Now the fan runs too fast all the time.
A online search revealed that the front panel on/off wires have a thermal sensor. A visual inspection of my sensor revealed no obvious defect so I cleaned it with denatured alcohol and a Q-tip.
Could the thermal sensor be my fan-too-fast problem?
08-21-2018 09:16 PM - edited 08-22-2018 08:03 AM
Yes.... that can be the problem. You state "fan" singular. Is it the front case fan, the rear case fan, or actually all fans?
Look up 455796-001 on eBay and for 16.00 USD you can get a used replacement front on/off switch cable assembly (which includes the ambient air temperature sensor that is zip tied to the metal grill out front). You can then test this idea out. It is not a difficult replacement procedure at all.... roughly 10 minutes. The idea is that if the HP motherboard fan control firmware system sees abnormal too low or too high ambient air temp coming into the case it will fail-over to ramping most of the fan RPMs up. The abnormal temp sensed could be a true reading or a false reading. The thermisitor rarely goes bad but it can happen and give a false high (or rarely a false low) temp reading back to the motherboard.
Alternatively, if you have only one fan with too high RPMs it could be that the PWM controller on that fan's motor is failing to get the message to slow down from the motherboard. The fan receives 12VDC input power, and if there is less and less PWM braking the fan runs faster and faster. HP has chosen fans that generally go quite fast if they get no PWM braking. So, you can look at the fan's label side to see if it has a HP part number, and search for one of those. You can use pretty much any HP PWM case fan that fits for this.... until recently those generally had a red-brown plastic color as the plug plastic and did not use the conventional white 3-ridged PWM fan plug morphology. Just two side ridges, and 4 pin holes. The 4th wire is the PWM control, and that wire could be broken, also.
Those are easy to find if you spend a bit of time on eBay.
08-22-2018 02:20 PM
Have you used part of a can of compressed-air to clean-out the insides of the power-supply?
Or, used that air on the heat-sink on top of the processor?
Or, between the front of the chassis and the plastic front-plate?
If any of those is "dusty", then it's possible that removing the side-panel adds more air-flow, to cool-down the system just below some "threshold" value, causing the motherboard slows-down the fan.
08-22-2018 07:04 PM
Thank you for your suggestions. I've tried them all with no luck.
The biggest clue to my high fan speed is this: when I wiggled the on/off wires the case fan IMMEDIATELY ran at near maximum speed for about 10 seconds before slowing down to normal (whisper quiet). Another wiggle had the same high speed result but on the last wiggle the fan only partially slowed. It now runs at about 1/2-2/3 maximum speed.
08-22-2018 07:46 PM
Thank you SDH for your reply. My computer only has a rear case fan; the one I'm referring to. No front case fan. The CPU fan seems to be running normally.
The biggest clue to my high fan speed is this: when I wiggled the on/off wires the case fan IMMEDIATELY ran at near maximum speed for about 10 seconds before slowing down to normal (whisper quiet). Another wiggle had the same high speed result but on the last wiggle the fan only partially slowed. It now runs at about 1/2 maximum speed all the time.
I'm not up to speed on my computer terminology; PWM? What does it mean & do? If I search on Ebay how do I identify a HP PWM case fan and know if it fits my xw4600 base workstation? By the motherboard plug? Other ways to ID the fan?
Thank you again.
08-22-2018 09:01 PM - edited 08-22-2018 09:05 PM
SDH kindly provided you with the correct HP part number for the xw4600 fan in a previous post and also gave you the web site to look on he then pointed out where the hp part number is located on the fan itself so i'm at a loss as to why you are again asking for this?
please go back and reread his post as all nessary information is included