whistling noise when I plug power

[nandan_ph]

Hello everyone,

A week before I got my custom built machine. Zap and lsv (forum members)helped me while I was trying to finalize the case, so thanks to them.

The config is:

Proc: Intel Core i7 - 3930 k @ 3.2 GHZ
Motherboard: Rampage IV GENE X79 mATX
Graphic card: Nvidia GTX 570 1280mb
Ram: 2X 8GB GSkill 1600mhz
Cooling: Corsair Hydro Cooling H60\
HDDs: 1X Intel 520Series 120 GB HDD
PSU: Seasonic s12D 750 Watts 80 plus Silver
(Zap suggested 550W PSU but my engineer refused and went on using 750)

Today I added one Seagate 7200 RPM Hard drive and now when I plug in power cord, I hear (not so loud) whistling noise, even before I start my PC.

My machine starts properly and haven't crashed. CPU temp is constantly between 34-37 c. But there is this constant whistling noise.

If I unplug dvd rom and the 1TB Seagate hard drive, the sound disappears.

Can anybody please help me? Is this sound normal?

Thanks
Nandan

 

[mindless1]

Normally I'd write that it's probably that your PSU has a loose inductor or transformer windings, but only the 5VSB rail should be active before the system is turned on so it is a mystery to me why unplugging two drives which don't use 5VSB would make a difference.

 

[sm625]

What about 3.3V? As far as I know, all three of those voltages should be zero until you hit the power button. If plugging in a drive is causing your psu to start making noise, then there has to be power on one of those lines when pc is in standby. I would find out which one, and why.

 

[mindless1]

^ plugging in power cord doesn't put the system in standby, and none of the power rails from an SATA connector (should be) are active, but just to rule that out it's worth checking with a multimeter.

3.3V (3.3VSB) can be found on some boards when soft-off, but it's regulated down on the motherboard from the PSU 5VSB rail and not the same 3.3V rail as on the SATA power connector.

One question is whether the change in noise is reproducible. For example on some PSU the power leads aren't very tightly bound to the PSU casing and the mere act of pulling on one could put pressure on the PSU PCB, which in theory could slightly change the tension on the windings of inductors soldered to it. Seems far fetched but something unique or odd is happening, not the normal faults we usually see.