Question Acer Aspire desktop CPU fan not running

[In2Photos]

One of my co-workers is using an Acer Aspire desktop. When she came in this morning her computer was off and wouldn't turn back on. I did some troubleshooting and assumed the PSU was bad. Picked up a new one from Best Buy and, sure enough, the computer booted right up. I noticed though, that the fan on the CPU cooler wasn't spinning. I went into the BIOS to see if something was disabled, not much to change in there though. Smart fan is enabled which I assume adjusts the fan speed based on temps. But shouldn't the fan run all the time, even at low RPM? I tried turning the smart fan off, which didn't do anything until I reseated the fan header. Then the fan came up to full speed (over 4000 rpm according to a hardware monitor). That was way too noisy so I enabled smart fan again, but no matter what I do the CPU fan never kicks on. CPU temps hover around 60C without the fan running. Any ideas?

 

[killster1]

use a fan controller and plug it into a different header

 

[VirtualLarry]

Is this a stock Intel HSF? Replace it, the fan bearings are starting to seize. Let me guess, she owned it 3+ years, and never cleaned/dusted it (especially the CPU HSF)?

Edit: And, unless things have changed recently, Intel HSF "Smart Fan" settings, generally did NOT have a "fan off" setting, like modern GPUs do these days. Generally, they just ran them at a slow but inaudible setting, at the lowest setting. If it's actually stopping / not running, then that is most likely a bad sign, a sign that the HSF needs to be replaced. IMHO, and IME. (Rationale behind that is, at zero RPM, it would generate a BIOS "fan stopped alarm" signal, and BIOS would start constantly buzzing or beeping, if enabled / beeper present on mobo or chassis. So they just run them slowly, but not stopped.)

 

[In2Photos]

Is this a stock Intel HSF? Replace it, the fan bearings are starting to seize. Let me guess, she owned it 3+ years, and never cleaned/dusted it (especially the CPU HSF)?

Edit: And, unless things have changed recently, Intel HSF "Smart Fan" settings, generally did NOT have a "fan off" setting, like modern GPUs do these days. Generally, they just ran them at a slow but inaudible setting, at the lowest setting. If it's actually stopping / not running, then that is most likely a bad sign, a sign that the HSF needs to be replaced. IMHO, and IME. (Rationale behind that is, at zero RPM, it would generate a BIOS "fan stopped alarm" signal, and BIOS would start constantly buzzing or beeping, if enabled / beeper present on mobo or chassis. So they just run them slowly, but not stopped.)

Yes, this is the stock Intel hsf. I doubt the computer has ever been cleaned but surprisingly there was very little dust inside including the fan blades and heat sink. I'm beginning to wonder how long ago it stopped working. I'll look into a replacement.

 

[mindless1]

I am not as confident that you could trust an OEM to adhere to the normal way of doing things.

Using your finger, is the fan hard to rotate like the bearings are bad? You stated it spun at 4000RPM which would suggest to me that they aren't. That's probably full speed reached, while bad bearings should decrease the RPM by a significant amount if it manages to spin at all. I suspect the fan itself is fine, or possibly the connector is damaged and making intermittent contact.

I would closely monitor the temperature while running a stress test like Prime95 to see if the fan kicks in when the temp gets higher, and abort when it gets near 80C. Technically, it is safe for a CPU to operate at 60C without a fan running, but it is a bit curious that you had unplugged then replugged it to get it to work as fan connections tend to stay fine for the life of a system, unless someone had been inside doing upgrades, repair, or cleaning, and had bumped it. Do you think it is possible it was bumped and that cracked a solder joint on the fan header? If so, a new fan won't fix that.

 

[In2Photos]

I am not as confident that you could trust an OEM to adhere to the normal way of doing things.

Using your finger, is the fan hard to rotate like the bearings are bad? You stated it spun at 4000RPM which would suggest to me that they aren't. That's probably full speed reached, while bad bearings should decrease the RPM by a significant amount if it manages to spin at all. I suspect the fan itself is fine, or possibly the connector is damaged and making intermittent contact.

I would closely monitor the temperature while running a stress test like Prime95 to see if the fan kicks in when the temp gets higher, and abort when it gets near 80C. Technically, it is safe for a CPU to operate at 60C without a fan running, but it is a bit curious that you had unplugged then replugged it to get it to work as fan connections tend to stay fine for the life of a system, unless someone had been inside doing upgrades, repair, or cleaning, and had bumped it. Do you think it is possible it was bumped and that cracked a solder joint on the fan header? If so, a new fan won't fix that.

The blades spin fine using my finger, doesn't appear to be frozen or sticky at all.

I came into the office this morning to perform the tests you mentioned. the computer was already on and something in the background had the CPU at 100% usage. I have no idea how long it has been like this but the temps were 100C.

There is an additional fan header next to the one for the CPU. I tried that one as well, but no luck. I downloaded Speed Fan and tried to use it to get the fans going, but none of the options seem to run the fan. I'm wondering if the power supply failure has done something to the motherboard and none of the fan headers work. I'm going to try a molex to fan connector to see if the fan runs at all before I spend money on a new CPU cooler.

 

[In2Photos]

OK, I found a small 3 pin fan and plugged it into the header and it runs fine, so looks like a bad fan on the stock hsf. Can I replace it with any standard fan? Looks like a new one would screw in to the heatsink?

 

[aigomorla]

OK, I found a small 3 pin fan and plugged it into the header and it runs fine, so looks like a bad fan on the stock hsf. Can I replace it with any standard fan? Looks like a new one would screw in to the heatsink?

No its called EIST.

SpeedStep - Wikipedia

en.wikipedia.org

Plug it back into the top 4 pin header.
There is a reason why the fan has 4 pins and was plugged into a 4 pin header.
Also most OEM vendors will have a warning feature on that header, where if u dont have a fan plugged in, it will halt bios, unless you press a key, or set it to bypass in bios.

A 4 pin pwm header, they work a bit different then a 3 prong analog header which you plugged it in to test.

So when the CPU is not in use, and idle, the cpu will throttle itself down and downvolt it.
This will allow it to generate less heat, and draw less voltage.
This causes the PWM profile to activate to balance noise with hearing.

What the guys had you do, was test to see if the fan was still alive.
Now that you have confirmed it was alive, and its EIST kicking speed step to do that.

You can go into bios and change the fan profiles to someone a bit more performance if you like, but it will cost noise.

 

[In2Photos]

No its called EIST.

SpeedStep - Wikipedia

en.wikipedia.org

Plug it back into the top 4 pin header.
There is a reason why the fan has 4 pins and was plugged into a 4 pin header.
Also most OEM vendors will have a warning feature on that header, where if u dont have a fan plugged in, it will halt bios, unless you press a key, or set it to bypass in bios.

A 4 pin pwm header, they work a bit different then a 3 prong analog header which you plugged it in to test.

So when the CPU is not in use, and idle, the cpu will throttle itself down and downvolt it.
This will allow it to generate less heat, and draw less voltage.
This causes the PWM profile to activate to balance noise with hearing.

What the guys had you do, was test to see if the fan was still alive.
Now that you have confirmed it was alive, and its EIST kicking speed step to do that.

You can go into bios and change the fan profiles to someone a bit more performance if you like, but it will cost noise.

I believe my post may not have been clear. The stock fan is dead, it will not spin, regardless of where I plug it in. I was able to take a case fan from another PC in our office that has a 3 pin connector. I plugged that into the 4 pin header where the CPU fan goes and this test fan works. So I need to get a replacement fan for the stock heatsink. I picked up a $7 fan from Best Buy, it's an 80mm fan and it fits, but only has a 3 pin. So I'm thinking about this one from Amazon: https://smile.amazon.com/gp/product/B00ZB7OHXS/ref=ox_sc_act_title_1?smid=AEELF2HAVZFED&psc=1

 

[aigomorla]

I believe my post may not have been clear.

your right i completely misread the thread.

honestly at this point i would just get a new heat sink.

It looks like a standard 115x with bolt on.

But if you need a fan, don't want to go the route of new sink, i would prefer this...

https://www.amazon.com/Noctua-NF-R8-redux-1800-PWM-Performance/dp/B00KF7MVI2/ref=sxin_3_ac_d_pm?ac_md=1-0-VW5kZXIgJDEw-ac_d_pm&keywords=80mm+fan&pd_rd_i=B00KF7MVI2&pd_rd_r=f5fe45dc-2eb2-4f84-ab89-73aa36c992eb&pd_rd_w=VpvBK&pd_rd_wg=dhUt6&pf_rd_p=709d2064-e546-4799-9e66-b352ea89951f&pf_rd_r=1P5WBS8X32HWFD5N6PF7&psc=1&qid=1577745089&s=electronics