mcdonald@uxe.cso.uiuc.edu (09/19/88)
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
rlb@xanth.cs.odu.edu (Robert Lee Bailey) (09/22/88)
In article <45900151@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes: > >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 While its true that switching power supplies "whine", I doubt that the difference comes from CPU activity. If the power supply is really the culprit, it is more likely that disk accesses are placing an additional load on the supply, which may alter the frequency and/or volume of the whine. Another highly likely culprit, is the video monitor. Most monitors use a sync signal which falls in the range of 15-25 Khz. This, of course, is right at the upper limit of human hearing, which makes it that much more annoying. Since it is JUST barely perceptible to a person with very good hearing, it becomes that much MORE annoying when you realize that its there! My monitor has a very noticeable "whistle". The pitch and intensity will slightly vary as the screen changes. Mine was SO annoying to me that my solution was to add another LOUD fan to my system. This provided additional cooling to my CPU case, but, more importantly, it covered up the monitors whistle! To me, the drone of the fan is MUCH more tolerable (like white noise), and tends to be a soothing sound, whereas, the whistle is more like the proverbial Chinese water torture. Bob Bailey
cdold@starfish.Convergent.COM (Clarence Dold) (09/23/88)
From article <6319@xanth.cs.odu.edu>, by rlb@xanth.cs.odu.edu (Robert Lee Bailey): > In article <45900151@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes: >> >>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 Another possibility is the CPU heatsink! On the Intel 80186 and 80286 ( not sure about 386 ), the flat-pack CPU is held down by a flat piece of metal and a spring. This piece of metal can oscillate, and it seems to be associated with activity on the board. ... I've got my flame proof 'theory' suit on ... It really does happen. Try popping the heatsink loose, and snapping it back on. This was a prevalent, although low noise, problem on a multi-processor system that I saw several renditions of, also using a switching supply. -- Clarence A Dold - cdold@starfish.Convergent.COM (408) 435-5274 ...pyramid!ctnews!mitisft!professo!dold P.O.Box 6685, San Jose, CA 95150-6685
spcecdt@ucscb.UCSC.EDU (Space Cadet) (09/23/88)
}In article <45900151@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes: } }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 It may also be your speaker. My fan and hard drive made enough noise that I recently made long cables for my monitor, keyboard, speaker, printer, and reboot switch and put my CPU in my closet. I really like the relative quite I have now, but I immediately discovered that the speaker produces sound even when it is "off". The loudness and tone vary according to what the machine is doing, but it isn't related to any i/o (drive, com port, monitor, etc.) I assume the sound is leaking from one of the busses and perhaps has something to do with patterns of memory or card access. John DuBois spcecdt@ucscb.ucsc.edu ...!ucbvax!ucscc!ucscb!spcecdt
awylie@pyr1.cs.ucl.ac.uk (09/23/88)
I dont think that switching power supplies ever change their frequency. Does the whine come from the system unit or from the monitor?
jsf007@killer.DALLAS.TX.US (Steve Fintel) (09/23/88)
In article <6319@xanth.cs.odu.edu> rlb@cs.odu.edu (Robert Lee Bailey) writes: >In article <45900151@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes: >> >>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. [text deleted] >Another highly likely culprit, is the video monitor. Most monitors >use a sync signal which falls in the range of 15-25 Khz. This, of >course, is right at the upper limit of human hearing, which makes it >that much more annoying. [text deleted] I also have a PS/2 Model 80 in a quiet room, and I also get the high pitched whine. In my case, it happens (intermittenly) when the machine switches in and out of protected mode. It is definately NOT the video monitor (I have connected two different monitors to this machine - further, it whines with the monitor switched off). In either case, it's quite irritating even though it doesn't seem to bother my dogs. Anybody else have any ideas on what might be causing it??? Steve Fintel killer!jsf007
is813cs@pyr.gatech.EDU (Cris Simpson) (09/23/88)
In article <5606@killer.DALLAS.TX.US> jsf007@killer.Dallas.TX.US (Steve Fintel) writes: >I also have a PS/2 Model 80 in a quiet room, and I also get the high pitched >whine. In my case, it happens (intermittenly) when the machine switches in >and out of protected mode. It is definately NOT the video monitor (I have >connected two different monitors to this machine - further, it whines with >the monitor switched off). In either case, it's quite irritating even >though it doesn't seem to bother my dogs. >Anybody else have any ideas on what might be causing it??? It was reported in several trade rags (infoworld, etc.) that the 80 whined when using the 387. It was supposed to be fairly loud. I have a Dell Sys 200 with a 10Mhz 287. There is a quite noticeable whine when doing any FP intensive stuff, such as a(n) FFT. Running Pspice can be maddening. None of this matters if it really is going protected that makes the whine. In such case, never mind. cris -- ||...despair! Despair I can handle, it's the hope... J.Cleese,Clockwise || Cris Simpson is813cs@pyr.gatech.edu GA Tech Atlanta,GA ...!{akgua,allegra,amd,hplabs,seismo,ut-ngp}!gatech!gitpyr!is813cs
marco@hpmcaa.HP.COM (Marco Dalla-Gasperina) (09/24/88)
Check the back issues of InfoWorld... I remember reading this (I know, it sounds really weird). There was a problem with the model 80 which caused a high pitched whine. As I recall it was related to the numeric co-processor. I remember I laughed out loud reading this. marco
mcdonald@uxe.cso.uiuc.edu (09/25/88)
>Does the whine come from the system unit or from the monitor?
I tried investigating further. It definately comes from the system
unit. It really isn't "loud" though I originally said that. I
tried removing the cover to listen in various places, but
when I did that I could no longer hear the difference between
idling and running something, as the fan noises were much louder,
relatively.
I simply put this on the net as a curiosity, as something different
from the flame wars in comp.lang.c.
Doug McDonalddaemon@watcgl.waterloo.edu (System Processes) (09/26/88)
:eywords: From: smvorkoetter@watmum.waterloo.edu (Stefan M. Vorkoetter) Path: watmum!smvorkoetter In article <5606@killer.DALLAS.TX.US-> jsf007@killer.Dallas.TX.US (Steve Fintel) writes: ->In article <6319@xanth.cs.odu.edu-> rlb@cs.odu.edu (Robert Lee Bailey) writes: ->->In article <45900151@uxe.cso.uiuc.edu-> mcdonald@uxe.cso.uiuc.edu writes: ->->->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. [text deleted] ->I also have a PS/2 Model 80 in a quiet room, and I also get the high pitched ->whine. In my case, it happens (intermittenly) when the machine switches in I have an IBM PCjr, with a Racore expansion chassis. It too whines, depending on what it is doing. Turns out to be the power supply in the expansion chassis. Touching various parts (don't try this, switching power supplies have 1000's of volts in them in places) caused the whine to stop. The reason the whine comes and goes is that the power supply will oscillate (switching supplies are supposed to oscillate) at different frequencies, depending on the load. If I do lots of accesses to memory above 128K, the whine goes away (this memory is powered by the expansion chassis' power supply) as the load on the power supply goes up. Similarily if I access drive B. I tried to put some silicone rubber on the parts that whine, with no luck. Wedging an eraser between the offending component and the heat sink next to it resulted in no whine, but a smell of burnt rubber. I guess I just got used to it by now. I can still hear it quite clearly if I focus my attention on it though. Stefan Vorkoetter
wtm@neoucom.UUCP (Bill Mayhew) (09/29/88)
I too have an IBM model 80 computer (16 MHz "ancient" version). I started out with the IBM 70 meg ESDI drive, but later switched to a Micropolis 330 meg ESDI drive. I've used both msdos and Xenix 2.2.2. The compute emits a quite noticable whine around 12 to 15 KHz, depending on what is going on in the system. The noise may be, but is fequently *not* related to disk activity. The whine is present with the monitor *off* or on; makes no difference. The whine does not come from the vicinity of the power supply; it is near the bottom of the case. With the cover off, the sound seems to be coming from the 80386 and/or 80387 or at least something very near the CPU chip itself (t'aint the speaker neither, as I tried unplugging it). Curiously, as the last poster noted, the whine is just about the loudest while msdos is in a keyboard wait. It wouldn't surprise me too much to find that the CPU chip is the source of sound. That is a pretty big hunk of silicon realestate there. Depending on what the chip is doing, the power drain can change markedly, thus the whine might actually be due to thermal effects or piezoelectric effects .. perphaps something like the solid state beepers on microwave ovens. There was also an article about "continuously beeping" model 80s about a year ago in Infoworld. So there; it isn't your imagination. I haven't seen any mentions in more scholarly things such as IEEE journals, or whatever, yet. --Bill