I bought a pc my friend built about 2 months ago. I used it for the first month non-stop and it was quiet as can be. I went about a month without using it and turned it on today and the fan has done nothing but run at full speed.

Any suggestions? Thanks in advance.

I am not sure the motherboard brand, like I said my friend built it. U can tell you it is a P4 1.6ghz processor 1 gig of ram. 1x 512 2x256

I went into my bios settings and did see anything about fan control. I am thinking it maybe set just to run all the time.

Also I opened up my computer and it seems to be the MPU cooler fan that is doing the non stop running.


directly under the part wher ethe cord plugs in is a red switch inside a slot that looks like an H

115 is showing and if i flip it 230 is showing. Does that matter?

I don't know the answer to your problem, however IF you are located in the USA, DO NOT flip the switch to 230V. That would blow your system.

The 115/230 voltage settiing should be that which is the incoming voltage at the wall outlet.

If by MPU you mean CPU, maybe a new name, but if you mean the fan/heatsink that sits atop your chip on the motherboard you don't want that to stop running my friend. If it does your chip fries! Less than a minute I think is the going time for a chip without cooling. If that is making a noise then I would replace the heatsink and fan both, paying careful attention to putting good thermal paste between the new heatsink and fan before installing it. About the size of a grain of rice is what I've used. You don't need a whole lot of it at all. You also could just take the heatsink/fan off and clean it good of the old thermal paste and then put new on and put it all back together and see if that helps. If the fan is running at full speed then it is maybe sensing that the chip is too hot.
It could be that the computer after long disuse just needs to warm up good and get itself going again. I've seen some that do that. I had one myself. But the fan running at full speed as you say and making a noise is not a good sign and I would really look into replacing the heatsink/fan as soon as you can. Make sure it's that though, it's very hard to tell where a noise is coming from. Could be the PSU, could be the fan on the video card if there is one, could even be a case fan. So really track down where it's coming from. Actually could even be a HDD getting ready to go, they make some strange noises.
If it wasn't doing it before and no one has changed any settings then I don't see how anything could be different. Settings don't change themselves at least in my limited knowledge and I stress that I have limited knowledge.
Also make sure you are grounded when poking around inside a computer. ESD can cause a lot of problems and damage your system.
Hopefully someone will come by with more ideas.