I've just got this problem a while ago in a custom built PC.
This computer isn't finished yet, so I don't turn it on a lot (I still need decent ventilation, a decent case and a CPU Cooler).
To the point:
I was watching some HD anime on this PC when I suddenly started hearing this not-so-loud but perceptible buzzing inside my case. In a matter of 2-3 minutes it was getting louder, so I turned off the PC to avoid any possible damage.
The buzzing sound was intermittent. It would remain on for like 2-3 seconds, go away for 8 or so, and again (sometimes louder than before).
After turning off the PC, I went behind the case to turn off the PSU, and felt a little electricity in my fingers (not a jolt, but the feeling there's current there). By the way, this computer is connected to a basic surge protector, no ground (house outlets have only 2 holes, not a third for ground).
I'm pretty afraid to turn on the PC right now and check the noise origin, since I'm in Bolivia right now, and I'm using NewEgg-bought components, and if something would be damaged by turning it on back without solving this first, the recovering and warranty procedures would be painful as hell. They are practically new (bought them 5 months ago, used them for like 1 month).
The sound appears to come from the central part of my case (somewhere near the CPU fan). Recently, I posted a question here regarding this noise coming from what I believe was the CPU fan too.
When I start the PC up, the CPU fan sounds like a helicopter (not that loud, but like if it is getting speed).
This "humming" sound last for like 30 seconds, raising it's frequency quickly until the intermittent humming isn't intermittent anymore, and I get to a "stable" state of noise.
I'm not doing overclocking, by the way, and I don't leave the computer on for too much time (fearing an overheat).
I'll list all my PC components here:
MoBo: Asus M4A89GTD PRO/USB3
Proc: AMD Phenom II 1100T x6 with stock HS (used AS5 for TC)
RAM: 2x4GB G.Skill Ripjaws 1333
GPU: XFX 9400GT 1GB (pretty old)
Primary (OS) Old Maxtor 80GB with a recent problem in damaged sectors after a power shortage. Filled with 0s everywhere and reused for OS.
Secondary: Hitachi 500GB Can't remember the details about it.
SMART report on the first one indicates 65 reallocated sectors. The second passes.
PSU: XFX PRO650W Core Edition
Optic Drive: Asus DVD-RW
Case: Generic SuperPower case. 1 HDD fan installed and no back fans (just a PCI slot one I bought from newegg)
PSU is top mounted, fan pointing towards MoBo.
Faulty Reset Button I disconnected and never used again (still lying somewhere inside the case).
Front panel USB and audio work without problem. No static shocks so far.
Data I constantly gather with AIDA64:
CPU Temps: On idle, around 42C for CPU, around 34-35C for Cores.
CPU Fan: Usually around 2500 rpm
GPU Temp: Gets around 80C when playing Blu-Ray anime.
GPU Fan: Idle around 50%, around 80% on load.
MoBo Temp: Around 30C
HDD Temps: Primary around 36C, Secondary around 32C
SMART data was taken from the AIDA64 report too.
One thing maybe worth mentioning. Windows startup is somewhat slow considering the RAM and Proc. I know this is also related to the HDD quality and speed, but it takes like 1:30 minutes to get to a working desktop from power up.
Maybe it's the HDD?
Thanks in advance for your help. I hope to hear from you soon enough.
Feel free to ask any info you might need to help me diagnose this, ok?
Nope, I discarded the last one I had. Could it really be the problem?. It practically brand-new.
Anyways, in case I find one, I'll try it.
The buzzing isn't exactly an electric buzzing, sounds more like a mechanical buzzing (friction somewhere, maybe?).
As it cannot be ruled out, what kind of components would make an electrical buzzing sound that lie around the CPU fan?
As for the current, it felt more like a little static shock (with no jolt nor arc), nothing that would numb my finger.
The system worked stable during this episode, no lock-ups, no attention or error pop ups.
By the way, I forgot to tell you about another issue with the stock fan. When turning off the PC, a split second before everything powers down, it sometimes accelerates (maybe to the top of it's capacity, it's kinda loud) and then turns off.
This time it did the same, interrupting the buzz almost instantly and then powering down.
Oh, and according to AIDA64, volts provided to each of the lines were fine. 0,01-0,03 volts over the line requirements. I'm not completely sure this would be relevant to the subject, but it might help too.