Hmmm... "Softer and lighter" is wierd; my first guess was an alarm - the hardware monitoring, that warns you at a preset overtemp, or if a fan stops (or, more likely, 'losses contact' with the fan sensing circuit momentarily), has a pretty unique tone, but it's typically louder than the 'BIOS beeps' - I gots to ponder some more...
Yeah - had kind of a comical one of those - someone posted here, said his machine was 'making a bizarre sound', and put up a pointer to a 'Dipstick'Tube video he had made; caught two seconds of it, said "Yup - that's a fan alarm, alright!" I've heard tell, too, of 'noises' from undersupply of video cards, but have never been able to really experiment, as I don't have anything that pulls enough current... Gonna change that, though - recently 'stumbled over' CUDA, which led to OpenCL - gots to git me sum o' dat!
Question now is the battle between my two decade long disgust with nVidia, their crappy support, their paranoid marketing moves, and their secretive documentation (but, their monster Tesla CUDA card ), and my fear that having been 'snapped up' by AMD is ruining ATI; guess the 'hole cards' will be shown at the end of the month, when, theoretically anyway, the new-gen Fermi cards are slated to hit the market...
I'm still thinking about this one, though - really not a lot of solid-state stuff that can make a noise - most everything I've ever had to track down has tuned out to be poorly wound or dipped inductors, and they'll usually 'squeal' at whatever frequency (or harmonic thereof) is being pumped through 'em - not a lot of mid-audio stuff involved - usually stuff only your dog can hear clearly
I too have heard squeals in bad caps but they are always continuous or die down eventually. A soft beep is definitely different. I still say an alarm of some sort. Just a matter of loading the Gigabyte tools that monitor the numbers and seeing if anything registers.
As for nVidia, I've gone back and forth between them and ATI (with some Diamond and Matrox thrown in over the years) but have always had the better luck (and better software experience) with ATI, even the new AMD-led products. I think it comes down to experience using and satisfaction with previous products that will lead you to your choice. Right now, my year-old Sapphire Radeon HD4870 1GB works fine though wouldn't mind trying DirectX11 with a newer card!
I tried that earlier without success. The strange thing is beep disappear whenever I open the sound recorder ( comes with Window 7 ) to record that strange beep . I will try that with MP3 recorder and send it to you. I'm just wondering if it's something to do with sound chips/components/drivers.