Buzzing from Motherboard

[southpaw117]

Last week, I put my computer to sleep before going to work, as I usually do. When I got home, I unplugged the monitor to use it elsewhere. When I plugged it back in and woke the PC, there was no image, the screen was completely black. I figured it was just an issue with removing the monitor. I pressed the sleep button but nothing happened, so after a minute I turned off the PSU.

Upon turning it back on, the face lights lit up with the exception of the power button light, all the fans were spinning, but the motherboard started making a consistent buzzing noise, and there was no image on the monitor. It seems the computer will power on but won't boot up. I installed a new PSU and have been toying around with removing components, but it's always the same issue.

What may be the issue?

 

[Lutfij]

*Try and isolate where the buzzing is coming from.

1| Please pass on your full system's specs inclusive of your OS. You should also pass on the parts you've used for troubleshooting and ruling out whether some are alright or faulty(like the PSU).
2| You may want to tear down the system and breadboard it. In the interim period (while tearing down) with a flashlight, inspect each and every one of your components for any swollen caps, burn marks.

 

[southpaw117]

The buzzing is coming from the motherboard's "speaker", the little black cylinder with a hole.

My PC is a modified Acer Aspire from 2008

Corsair CX 650M
Intel Q6600 @ 2.4GHz
GeForce GT 740 FTW
2x 1GB DDR(2? I forget, but each stick says 1GB.2Rx8.667. They came with the PC)
Windows XP SP3 / Windows Vista

The HDD is a Hitachi, Model HD725032VLA380
I'm not sure about the motherboard. It says Acer Module EG31M

Nothing looks blown or burnt, and everything is connected securely.

I tried all that follows; all resulted in the same buzzing:

Removed GPU
Tried only one RAM stick
Tried the other stick
Unplugged HDD

The PSU is brand new as I bought it without doing any initial testing.