Remember our discussion awhile back about whining noises coming from a Mac (usually a 7500) after installing the 604 120 processor upgrade? Joel Shoemaker reports that PowerLogix told him that the problem was due to "lack of grounding clip. The Apple processor upgrade sold in retail channels, as opposed to the bulk cards that Apple dumped, comes with a little grounding clip that attaches from the heat sink to the chassis of the computer. We believe the whine is RF and this grounding clip should cure it. Or any patch cord (such as one available at Radio Shack) with alligator clips on both ends should work." However, when Joel tried out this advice, it had no effect on the whine!
Update: Several readers once again pointed to the power supply as the likely source of this whine. Here is one particularly interesting comment in this regard: "The 604 based cards draw more power that the original 601 based card therefore it puts strain on your power supply. A better choice would be to upgrade to a 604e based card which uses less power. This would fix the whine and run at a faster speed. The 604e processor uses less power at the core voltage and is a much more efficient chip."