CPU fan is making a strange noise

I've had this computer since March and I'm using the stock heat sink it came with. Recently I've noticed that sometimes programs will be unresponsive for 4-6 seconds and then it will go back to normal. The same thing can be said about the mouse, sometimes it doesn't even move. I took apart the side panel of my case and noticed that the CPU fan was making the noise. It sounds like a dial up modem, but a lot more silent. This noise can only be heard up close and eventually it goes away before starting to make the noise again. My CPU temps are normal, 31 on idle and usally 45-50 when I'm playing a game. The stock fan never stops spinning either. Maybe the motherboard has something to do with this? I haven't changed anything or added any new hardware since putting it together in March nor have I replaced the thermal paste because the temps were always low to begin with.

Here are my specs

Operating System
Microsoft Windows 7 Ultimate 64-bit SP1
CPU
Intel Core i3 3220 @ 3.30GHz 36 °C
Ivy Bridge 22nm Technology
RAM
8.00 GB Dual-Channel DDR3 @ 798MHz (9-9-9-24)
Motherboard
Gigabyte Technology Co., Ltd. B75M-HD3 (Intel Core i3-3220 CPU @ 3.30GHz) 28 °C
Graphics
G236HL (1920x1080@60Hz)
AMD Radeon HD 7800 Series
Hard Drives
932GB Western Digital WDC WD10EZEX-00RKKA0 ATA Device (SATA) 31 °C
112GB KINGSTON SV300S37A120G ATA Device (SSD) 29 °C
Optical Drives
No optical disk drives detected
Audio
AMD High Definition Audio Device

I apologize if I added this thread in the wrong topic.

I can also record a video of the sound I'm hearing

Do you have another fan to replace it? It's good to have spare fans available.

Although fans usually last longer than seven months, it's not uncommon for a fan to go bad. If you have fan monitoring software, you could make a note of the speeds and watch for abnormal speeds or behavior.

Are you sure the noise is coming from the fan? I've never heard a fan with a bearing problem sound like a dial-up modem. Although, a spinning fan blade that is rubbing against something it shouldn't be might make an unusual sound.

I'm not familiar with your cpu fan-heat sink assembly, but you should check it carefully. I've seen an Intel cooling solution were it was very easy to have the fan misaligned on the heat sink and make a rubbing noise. Turn the system off and rotate the fan with your fingers to see if you can detect any misalignment and fan blade contact with the heat sink, mounting system or electrical wires. Give the fan a good spin to see if it behaves as expected. Be careful not to damage anything and I would unplug the PSU as an added precaution.

Regards

It actually sounds like a HD is loading but I checked the hard drive and it seems to be working fine. It's probably just a bad fan and I need to replace it. I'm not sure why programs sometimes seem to be unresponsive sometimes.

Here's a video. Hopefully this was helpful.
VID_20131010_031521.mp4 - YouTube

It does sound like the hard drive. The fan sounds steady and consistent. The high speed chirping sounds like a hard disk. What's the make and model of your hard disk? You should contact your hard disk manufacturer's tech support and ask about what's normal. It may be nothing to be concerned about or it could be the early indications of a bad drive. You don't know unless you consult with someone knowledgeable on that particular model.

You can also monitor the drive's SMART attributes with a program such as GSmartControl. It's a free download and very useful. GSmartControl is basically a GUI for smartmontools. If you download both, GSmartControl will use the latest version of smartmontools. If your system is 64-bit, don't select the 64-bit option during the install of smartmontools. GSmartControl will may experience a conflict if you do.

I received a warranty replacement drive from Seagate yesterday and sent it back because it had a very noticeable vibration when compared to my other two that were the identical same model and firmware.

Regards

Put your fingers on the hard disk and check to see if you can feel vibration. You should be able to feel a faint vibration, but a strong and steady vibration may be an indication of a bad drive.

Regards

Western Digital WD Blue WD10EZEX

I just ran some tests and no errors were found. I also ran HD Tune and still nothing is wrong. I'm using an SSD for my OS so I can try to unplug the WD drive and see if the case is still making a sound

Unplugging the hard drive didn't seem to do anything. The noise is still coming from the CPU fan. Also Youtube videos are randomly freezing for 5-10 seconds before playing.

Noises can be very hard to find as they seem to come from one area but it may be somewhere else. Have you checked the fan/s on your graphics card as they can also get noisy.