I just finished upgrading my Dell Optiplex 780 to Windows 7 64-bit. The tower was producing a very irritating high-pitched noise after this upgrade. After a bit of searching, I found this discussion that seemed to match my problem:
http://en.community.dell.com/support-forums/desktop/f/3514/p/19292677/19546282.aspx
I tested the BIOS setting change for C State Control suggested by carl.hobbs and petewitt. It solved the problem instantly.
I had a high pitched noise problem too. The computer is a Dell Optiplex 780 Windows 7 Pro 64-bit. It only sounded when the hard drive wasn't active.
ReplyDeleteIt seemed to be coming from the motherboard speaker. The speaker is to the right of the CPU. It started for no apparent reason when I turned the computer on in the morning.
The only unusual thing I had done was to install the ATI Catalyst Omega 14.12 video drivers the previous day. I had to turn off Fast Boot and turn off SERR error messages to get the drivers to install.
The computer worked fine all evening then in the morning it started buzzing. Turning off Performance-C State Control fixed the problem.