CPU Fan is on high all the time

[alegator]

I never had this issue in the 8 years I'm using this PC. I left home two days ago so I left the PC unplugged. Today when I came back and powered on the PC everything seemed normal but after about 5 minutes of using the PC the CPU fan started spinning at high RPM and making the normal loud noise when this happens (sounding like a hairdryer on high). Since then (about 5 hours already) the CPU fan has kept working at high RPM and I was unable to set it to low speed. I opened the tower and checked that all cables and heatsink is tight. Unfortunately there's no setting in the BIOS that controls the CPU fan.

What could be causing this? Will replacing the CPU fan by a new one fix this? Thanks.

MY SYSTEM: Dell Dimension 8200, P4 3.06GHz CPU, 2Gb RDRAM

[lowellriggsiam]

You are sure that it is the CPU fan and not the one on the video card? When the fan is running what is the CPU temp?

[ocgw]

I never had this issue in the 8 years I'm using this PC. I left home two days ago so I left the PC unplugged. Today when I came back and powered on the PC everything weemed normal but after about 5 minutes of using the PC the CPU fan started spinning at high RPM and making the normal loud noise when this happens. Since then (about 5 hours already) the CPU fan has kept working at high RPM and I was unable to set it to low speed. I opened the tower and checked that all cables and heatsink is tight. Unfortunately there's no setting in the BIOS that controls the CPU fan.

What could be causing this? Will replacing the CPU fan by a new one fix this? Thanks.

MY SYSTEM: Dell Dimension 8200, P4 3.06GHz CPU, 2Gb RDRAM

You don't have "smart fan" in the BIOS?

ocgw

peace

[alegator]

There are 3 fans in my PC: the CPU fan, the PSU fan and the Videocard fan. I opened up the tower and definitely it's the CPU fan (I stopped it by unplugging it and the noise comes from the CPU fan).
There's no "smart fan" or any other fan related setting in the BIOS. There's no CPU temperature sensor in the mobo so no way of knowing the CPU temp. The 4 diagnostic lights that come with my system are all OK (green). The PC boots normally into Windows and Device Manager indicates all normal.

[budz]

You'll probably have to remove the cpu fan and clean off the old thermal paste. Then reapply new thermal paste when you buy a new cpu cooler.

Here's a easy P4 cpu fan to install, it's the Zalman CNPS7700, $32.99 from SVC.com.
http://www.svc.com/cnps7700-cu.html

[ocgw]

You'll probably have to remove the cpu fan and clean off the old thermal paste. Then reapply new thermal paste when you buy a new cpu cooler.

Here's a easy P4 cpu fan to install, it's the Zalman CNPS7700, $32.99 from SVC.com.
http://www.svc.com/cnps7700-cu.html

Maybe he can get away w/ just reseating the hsf w/ new thermal paste?

ocgw

peace

[redwudz]

There's no CPU temperature sensor in the mobo so no way of knowing the CPU temp.

Have you tried using a program like HWMonitor: http://www.cpuid.com/hwmonitor.php to check temperatures? I don't know of a MB or CPU that doesn't have temperature monitoring built in. But who knows with Dell. If all else fails, use a simple test: Put your finger on the base of the CPU cooler. If it's so hot you burn your finger, you have a overheat problem.

If the CPU HS is clean and not packed with dust, and the base is cool to the touch, then you have a malfunctioning fan controller on the MB or in BIOS, though you may not see settings there. If it's very hot, then you should probably find out why. Failed heat sink thermal compound can cause that, but even then it shouldn't make it run really hot. A loose heatsink would be more likely. Too high a CPU voltage can also cause overheating.

You can get fans with a built in fan speed controller, or add a in-line fan speed controller to the existing fan. But I think there are other problems.

[budz]

^^^Yuh, he could do that too....But if it continues might as well buy a new cpu cooler.

[redwudz]

True, but it may also just be a failed RPM sensor on the fan. But the most important thing to find out is if the CPU is running too hot. That can shorten it's life. And if the OP has never removed a heat sink that may be 'glued' to the CPU, he could be in for a not-so-fun project.

[ocgw]

^^^Yuh, he could do that too....But if it continues might as well buy a new cpu cooler.

ummm....only reason I mentioned it was I don't think he is oc'n and a Zalman just might be soooomewhat of an overkill in his dell

does look like it would fit tho'

ocgw

peace

[budz]

^^^there aren't too many socket 478 cpu coolers around and i'm assuming he's not used to removing/installing a new cpu cooler. that zalman is easy to install which is why i posted it.

[ocgw]

^^^there aren't too many socket 478 cpu coolers around and i'm assuming he's not used to removing/installing a new cpu cooler. that zalman is easy to install which is why i posted it.

Sounds like a plan after he verifies his cpu is indeed hot

ocgw

peace

[darkknight145]

are you sure the fan is actually running at high RPM, and not just suddenly developed a noisy bearing? - quite often happens when PC hasn't been turned on for a while or has been physically disturbed.
Also as others have said check the CPU temp, all CPU's have temp sensor built in, just download some free software to check it.

[budz]

download HWmonitor which will give you the temp of your P4 cpu.
http://www.cpuid.com/hwmonitor.php

[alegator]

I cleaned the CPU fan thoroughly and for the last 6 hours has been working fine, at normal speed and without noise. So I guess the dirt was the issue. Thanks everyone for your replies!

You'll probably have to remove the cpu fan and clean off the old thermal paste. Then reapply new thermal paste when you buy a new cpu cooler.

Here's a easy P4 cpu fan to install, it's the Zalman CNPS7700, $32.99 from SVC.com.
http://www.svc.com/cnps7700-cu.html

Thanks budz, I did remove/reinstalled both the CPU and CPU heatsink when I upgraded the CPU about 7 years ago and reapplied thermal paste at that time. However, before doing this again, I wanted to try if simply cleaning the CPU fan would fix the issue, which it did. Anyway, thanks for the Zalman fan recommendation , maybe it's quieter than the fan I currently have installed, which came with my Dell. For that price I guess it's no risk trying it.

are you sure the fan is actually running at high RPM, and not just suddenly developed a noisy bearing? - quite often happens when PC hasn't been turned on for a while or has been physically disturbed.

Yes, I'm sure the fan was actually running at high RPM, it is the typical noise/rpm that develops when CPU usage is intense.
P.D.: There's no software that can report the CPU temp (I tried them all, HWMonitor, Lavalys Everest, etc), there seems to be no CPU sensor built in the mobo.

[ocgw]

[/quote]Yes, I'm sure the fan was actually running at high RPM, it is the typical noise/rpm that develops when CPU usage is intense.
P.D.: There's no software that can report the CPU temp (I tried them all, HWMonitor, Lavalys Everest, etc), there seems to be no CPU sensor built in the mobo.[/quote]

Most modern cpus have a temp sensor built right in them, not sure about yours

Your mobo doesn't have a cpu temp sensor because, it is a "Dell", out sourced from "Hell" j/k lolz

ocgw

peace

[budz]

alegator: Good to hear you solved the problem.