I didn’t see this issue covered in the “Computer Questions” sticky, so I guess I can ask it here.
I just installed a new mother board and now my CPU fan runs at top speed the whole time the computer is on. Before the new MB it would run at 100% for just a few seconds at start-up, and then slow down to a quieter speed. It even runs at full speed when the computer is in stand-by mode.
I downloaded a little freeware program that allows me to monitor (and theoretically change) the fan speed of the CPU fan and case fan. It changes the speed of neither as far as I can tell. It also allows me to monitor the temp of the CPU and MB. The CPU temp seems to be fine, hovering around 34C. Atleast that seems fine based on one page a found on the net for my CPU (celeron D 2.66mghtz).
I checked that I plugged in the CPU fan wire correctly. Other than that, I just don’t have a clue what to look for.
One thing that could cause that would be if your CPU is actually running high the whole time. Bring up task manager and click on the Performance tab. If you don’t have any applications running, it should be no more than 2-3%. If it’s a lot higher than that, you may have a virus in the background.
Is the heat sink dusty? There’s also a BIOS setting on some mobos called FOC or “Fan-off control”. Maybe the new MB isn’t set up properly, or it’s cheap and doesn’t have such a control. What’s the model?
Read the manual for your new motherboard. It may not support speed control, or if it does, it may require a specific hardware and software configuration.
Was the original fan header four pins? Is the new one four pins and does the fan have four wires? Some Intel motherboards use a four pin header/fan and control the fan speed with pulse width modulation (PWM). If you have a PWM fan and plug it into a three pin motherboard header it will always run full speed.
First off, let me say thank you for your responses. They are much appreciated by everyone at my house who has ears.
Thank you.
hajario - CPU is running around 1-3%, so I don’t think that’s the issue
Bryan Ekers - the heat sink is a little dusty, I’ll try that. I haven’t looked for that BIOS setting - will it turn the fan off completely until changed back to “on”? If so, that seems like asking for even more trouble than I’ve got now. MB Model
alterego - no, I just downloaded that fan speed program after the problem started. I had never even thought about fan speed before.
mks57 - the manual isn’t that thick, I don’t remember it mentioning speed control, it just tells you where to plug the fan in. I’ll look again when I get home.
yoyodyne - the original was a 3 pin. I’m wondering if I could have it in backwards even though there’s a little tab on one side that supposed to make that not happen. Do you think that’s a possible reason?
A popular item for this (rheostat for fan speed control) is the Zalman Fan Mate 2. Google/froogle it. $5-ish. I’ve got one and it works as advertised. Or you could find instructions to make one yourself.
Thanks again yoyodyne. My local Circuit City has a big fan / heat sink that says it’s for Socket 478, although it looks much bigger than the one I have now. Altough, the reviews on this thing scare me.
When you say rheostat I think of the knob on the wall that used to be popular to turn down lights with. I’m guessing that you’re talking about a much smaller model that could fit in a computer case. Can I find such a thing locally or at a specific internet site that you’re thinking of? I’m guessing it would go inline between the MB and the CPU fan and I would adjust it manually?