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From: dmurdoch@watstat.waterloo.edu (Duncan Murdoch)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Ringing CPU?
Message-ID: <1990Nov5.210559.5733@maytag.waterloo.edu>
Date: 5 Nov 90 21:05:59 GMT
Sender: daemon@maytag.waterloo.edu (Admin)
Organization: University of Waterloo
Lines: 19


I've got a Northgate 486-25, and have noticed that under certain conditions,
when it's in a loop asking for input I can hear a high pitched ringing
(maybe 8 KHz, but I'm not a very good judge of pitch).  For example,
if I boot with almost no drivers or TSRs except Borland's TDH386.SYS (the
driver for virtual debugging), I can hear the ringing when I'm at the 
DOS prompt, and it becomes much louder after I've run the debugger and
exited.  If I run a program, or just do a DIR, it stops until I'm back
at the prompt again, so I think it must be that I'm hearing the CPU
(or some associated circuit) resonating at the frequency of the input
loop.

Does anyone know whether this is a sign of an impending breakdown?  It 
seems to me that the CPU (if that's what it really is that's vibrating)
shouldn't vibrate enough to emit sounds, and if it does, is likely to
work itself loose from the socket.

Duncan Murdoch
dmurdoch@watstat.waterloo.edu