I tried the solution below and it worked on my HP 450 G4 laptop,
Certain lines of Asus laptops emit an intermittent high-pitched noise resembling an electronic signal.
The lines affected include the following:
eee PC 1201T
This noise has been variously described as a whirling noise, a chirping noise, a whiney noise, and a screeching noise akin to fingernails on a chalkboard.
This noise can be very irritating and have been the subject of numerous complaints to the company. The company has not been very responsive to these complaints.
The good news is that there is a fix for this problem. The process takes less than five minutes. I’m no expert, but the following is what worked for me. Follow these directions at your own risk! If you have a better fix, please let them in the comments for everyone’s benefit.
Click the Windows Start icon, and in the “Search Programs and Files” field type regedit
Navigate to the following folder:
HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Control \Power \PowerSettings \54533251-82be-4824-96c1-47b60b740d00 \5d76a2ca-e8c0-402f-a133-2158492d58ad
Click on ATTRIBUTES
On the top of the dialog box it should say DWORD
Change the 1 to a 0
Click on the Windows Start icon.
Go to Control Panel –>Hardware and Sound –>Change Plan Settings (for each plan that you use) –>POWER OPTIONS –>
Advance Power Settings –>Processor Power Management –>Processor Idle Disable
Set both of them to Disable Idle