For a few weeks now I've been noticing this very high pitched noise coming from my machine. I figured it was the water pumps or a fan. Last night it was driving me crazy, it's like a dog whistle and if you listen in on it for a few seconds, it has a terrible "brain melting" effect. So, I stopped the pumps and the fans, but it continued, stuck my head in there and to my surprise and confusion it was coming from right around the CPUs.
In searching around about this I did find a few others with the same issue. Apparently it is (suspect?) voltage regulators and/or capacitors. Others also said it can happen if you enable certain C states in the bios. Well, a few weeks ago I had turned on all of the C0/6/7 states. I've restored that to the defaults and the noise is gone.
Any thoughts? To be honest I really don't even know what C states are.
In other news, I again got the stones to try getting up to 105mhz and 2133 again, and it "just worked" with v5004 - seems stable so far.