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From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.sys.ibm.pc
Subject: Computer Whine
Message-ID: <45900151@uxe.cso.uiuc.edu>
Date: 19 Sep 88 14:51:00 GMT
Lines: 12
Nf-ID: #N:uxe.cso.uiuc.edu:45900151:000:595
Nf-From: uxe.cso.uiuc.edu!mcdonald    Sep 19 09:51:00 1988


I just moved my PS/2 model 80 from my very noisy lab to my nice 
quiet office. I now notice a very odd thing: When idling at the DOS
prompt the system box makes a loud, high pitched whine. When it
is actually running a program this ceases. The only explanation
I can come up with is that it is drawing lower power from the
power supply when idling, and that the supply is a switching one,
and hence going to a lower frequency. Then when the power requirement
goes up, so does the frequency, above the audible range. I this
correct? Why would the MSDOS idle loop draw less power?

Doug McDonald