I have a DG45ID motherboard with a C2Q Q8300, 4GB RAM, Intel X25-M 80GB SSD, 750GB HDD, one DVD drive, 650 watt power supply, latest BIOS (131), latest drivers, including RST in AHCI mode, Win 7 64bit, using the G45 onboard graphics.
This system has been just fine for months, none of the curious afflictions that this board can have, no fan speed surging, no inductor squeal, IDU running fine, I was pleased with this setup.
But of course I had to fool around, so I purchased a modular power supply by the same manufacture as I was currently using. I carefully removed the old PS and installed the new PS, and besides changing a case fan or two, nothing else was done, no other new hardware, same mouse, keyboard, monitor, nothing whatsoever.
So I fired it up and it booted up fine, all seemed normal. I checked the power supply with IDU and another utility, and noticed the 12V reading was slightly low, 11.987 V, plus or minus 1/100 volt. Certainly within normal range I would say, and I do not think I have a heavy load on this system. The PS is a 750 watt unit with a rated 60A 12V rail.
Next I noticed the motherboard inductors singing away as I have never experienced before, basically non-stop but rising and falling in volume and some on and then off again behavior. I have never had this in the past besides a couple quick "beeps" from an inductor when booting the system (and no I don't mean the BIOS beep from the motherboard speaker.)
Then the CPU fan surging phenomenon started occurring. I haven't had that since updating the BIOS months ago. Tried rebooting, enabling fan detection in the BIOS, checked BIOS fan settings, but the fan surging persists.
I then noticed I was getting flakey readings in the IDU and another hardware monitor (HWiNFO32.) Crazy motherboard temperature values (-90 degrees) appeared, and voltage readings for the three main rails would change places, i.e. the 12V column would show 3.3V, and vice versa. I have seen this in the past with an earlier version of IDU as well, but the current release has been working fine for me.
Meanwhile this PC otherwise is functioning fine. No BSOD, no glitch of any kind. I uninstalled IDU, flashed the BIOS with the current release (131) which I was already using, finished fine, checked BIOS settings, all were preserved. But no changes with the issues I have discussed.
I have always thought that the problems I have mentioned and encountered by others as seen in this forum are actually caused by the monitoring chip used on this board. Or are related to that chip and interference somewhere in the system. I should mention that I have always seen nonsense CPU temperature readings when using HWiNFO but that may be due to Intel giving the interval to the max CPU temp (as seen in IDU) rather than the actual temperature. I do see apparently valid values for individual core temps with HWiNFO, as well as MCH and ICH temps.
I wonder if I damaged something while changing the PS's, and I checked my new PS installation several times and I cannot find a problem. As I said this PC is otherwise running fine... so far, it's only been a few days with the new PS.
I am not expecting a magical cure to be offered by someone (I know, put the other PS back in... I'm considering that) and really just posted this to add to our knowledge/experience base (FWIW!) Frankly, given all that is happening with all the various hardware and software components within a PC, I feel it is a miracle that they function at all. Of course, I am open to suggestions. Thanks.