Concerned about uncertain computer noise

[Sofronitsky]

My new computer, assembled today (thanks everyone for your help) has been up and running for several hours now. XP loaded w/out problems and every thing's working fine. About an hour ago I noticed a strange straining noise coming from inside the pc. I took the side panel off to take a look but could not determine the cause. I'll describe it a bit more: It comes and goes... sounds fine for a few minutes then gets louder and then dies down. A bit like straining, or a motor running too hard (loud). I've allowed my computer to stay on and have been keeping a close eye on it... no changes after restarting and powering down for a while and then turning it back on. The sound is really not so alarming that I 'm worried about having it on, but I'd like to figure out just what the cause is, and see if there's anything I can do about it. I think it's either: REAR CASE FAN, PSU FAN, PSU ITSELF, or PROCESSOR FAN, but not completely sure. How should I go about checking things out? I think it would be ok to run it without the rear fan (w/ door open) for a short time to see if that's what's making the noise. But, it's obviously not so easy to check the other possibilities.

I noticed one other thing today. The processor fan stopped briefly (while pc was running...) and then started up again. This worried me, but it hasn't done it since then. Is it normal for the processor fan to stop spinning if the cpu temps are low? Or is this a sign of a damaged hsf that I should have replaced?

Thanks for the help... I'll probably need some more again soon but I'm nearing the end here : )

[TwoRails]

It sounds like a fan problem to me, too, but "ya never know..." Two methods to isolate the problem are: 1) a long bladed screw driver. Hold the handle to your ear and then touch the various components with the tip. The item with the problem will sound the loudest, and it's usually obvious once you find the problem item. 2) A hose, like a vacuum hose for a car, can sometimes be used, too, but it is more difficult to detect fan problems as it will also pick up wind noise.

[Sofronitsky]

thanks for the suggestion. I'll give that a try.

[Cricket]

Please post the specs for this computer. List all the parts by brand and model including the power supply.

If you suspect the problem to be one of the fans, just slow the fan blades by putting pressure on the center of the fan hub with your finger or some other object. If the noise decreases with the slowing of the fan blades, you've found the source of the odd noise.

The CPU heatsink fan shouldn't stop and then start while the computer is running. But it could be the bearings are just tight...give it a day or two to loosen up and it may never do it again.

Cricket

[Sofronitsky]

I ran the computer for most of the day and heard nothing. Strange. I was all set to get to the bottom of the problem today but everything was quiet. I guess I'll have to keep an eye (an ear in this case) on it. The HSF for the processor was fine too, fan didn't stop at all. Can't explain it.

PC specs:

Intel DP965LT MB
Intel E4400 (w/ stock HSF)
2gb corsair ValueRAM (667)
500gb seagate 7200.10
FSP Blue Sotrm II 500 Watt PSU
Coolermaster Cavalier 3
Case fans came with case - front 80mm intake 120 rear- out