Motor-like whine from CPU area

Question

I have an odd sound coming from the area of my CPU. If i was to describe the sound I would say it sounds something between like a air filtration system for a fish tank when it has no water to pump and an RC car when it's stuck.

I thought at first it was my water cooling system and removed it and then put the stock fan in. After awhile the same sound started again. When the computer is sitting idle with no programs open it's fine. If I open a browser and leave it for a few minutes is when it starts up again. I also noticed that when I close the browser after hearing the noise it fluctuates but doesn't stop until i shutdown my computer down. I checked all temperatures and they seem to be within their normal range of 30 - 40 C.

Specs:

CPU: i7 4770K 3.50 GHz,
MB: ASUS Sabertooth Z87 Armored,
Case: Phantom 410,
GPU: 2x 2GB 7850,
HDD: 500GB and 1 TB,
5x Case fans,
PSU: 750W

Note: Entire build is less than 7 months old.

Answer 1

Sometimes sounds, especially higher frequency or in tight spaces (and oddly shaped spaces) can be hard to locate. Check your power supply fan, maybe it's dirty or one of the bearings are failing. That would be a first guess. Also check any case fans you have installed. You could try unplugging them one at a time when the noise is happening to see if it stops.

There's also the GPU fan, although the pattern you describe doesn't seem correlated with GPU usage. The observed increase during periods of activity lends evidence to a power supply fan issue.

A less common, but still possible, source could be vibrations from one of the coils in the power supply, although that would tend to make a "purer" sound than what you seem to be describing. This is often just a quirk and not an indication of a problem, but can be annoying.

Other than that the only moving (or potentially vibrating) parts are in mechanical hard drives, but your symptoms don't sound like that plus you'd certainly notice other problems if that were the case (although if you do find it is your hard drive; back up and replace immediately). I guess there's optical drives as well but that makes very little sense given the description.

General troubleshooting here is to remove components when possible (i.e. case fans, graphics card if you can fall back on integrated graphics) until the noise stops. When there are no components left to easily remove you've at least narrowed it down. You can pull the PSU out of the case (but leave it connected) and more easily identify if it is the source. You can do the same with a hard drive. You've already ruled out your water pump.

If you find the source is a fan, clean it thoroughly (and carefully) first, and if that doesn't stop the issue then consider a replacement part.

Answer 2

I use a vaccume cleaner hose and pump hoses , or any tube even a paper towel tube , that is non conductive. put one end as best as one can to ear, and the other end you aim and point it at things until you locate the area where it seems the sound is loudest.
Another probably better method use a microphone like a lapel mic , and pass it through some amplifier or your sound card, and move it around to locate the sound. (many mics can have conductive cases).
While doing that you have to avoid smashing into fan blades, which doesn't help. Having 2 people can help, one listens and the other one points and avoids crashing into the wrong things.

I have used this method a few times, it has about a 50% success rate at pinpointing the item, even coil whine locations. If you have nice water cooling hoses it might be a way to get an ear on it.

Make sure it isnt comming out of your sound system, or from cell phone interferance, before climbing into the case. If it occurs with a CPU load or GPU load use benching programs to initiate a similar load as a constant while trying to locate the sound.

Jason C covered all the possible locations well, so this is just a long comment.