Crackling sound from pc casing with dimming lights?

I'm using Acer Aspire T180 with AMD Athlon 64 X2, Nvidia Geforce 8600GT, 2 Sata HDD, a DVDRW and Cooler Master 500W. My problem is that I'm hearing an intermittent crackling sound from the the casing accompanied with the dimming of the power lights (at the wall power point). This happens even before Windows is loaded so I know that it's not the hard disk. What could be the problem?





I have only recently installed the Cooler Master 500W after suspecting that the standard 250W PSU that came with the T180 was insufficient to power the 8600GT and 2 SATA HDD. Prior to that, the computer would randomly turn itself off without warning. This no longer happens but now there's the crackling sound. The PC works ok but I'm worried that sound could mean something else.Crackling sound from pc casing with dimming lights?
Its nothing else but just like some wire or such else component that is stucking with some fan or other device. Just check it and it will be ok...Crackling sound from pc casing with dimming lights?
It most defanitly sounds like a Power Supply issue. If you can, take it back (or send) to the store and get a replacement of the same unit and see if does the same thing.
aliens