Messages in this thread | | | Date | Sun, 05 May 2002 21:37:26 -0400 | From | Justin Piszcz <> | Subject | Re: Linux & X11 & IRQ Interrupts |
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Ahh... Thanks for the information.
"David D. Hagood" wrote:
> Justin Piszcz wrote: > > > With the console speaker attached, it can be clearly heard, as well as > > performing fast packet movements (nmap (with insane option)) or such you > > can literally hear the packets. > > What you are hearing is the noise in the computer's power supply. As the > load on the power supply changes, the voltage changes by a few tens of > millivolts, and that is the noise you are hearing. > > This primary reason you don't hear this under Windows and you hear it > under Linux is that Linux will shut the processor off when there is > nothing to do, greatly reducing the load on the power supply. When > something happens, like a mouse interrupt or a network interrupt, the > CPU springs back to life, drawing a burst of power from the power supply > and momentarily bringing the voltage down a bit. This cycling of the CPU > happens in microseconds. > > Windows, especially older versions of Windows, doesn't do this - when > there is no work for the CPU, it spins in a busy loop looking for work. > As a result, the load on the power supply never changes. Of course, your > system will also run hotter and burn more power. > > If this bothers you, you could try getting another power supply (one > that is "stiffer" and less prone to voltage sag) or you could run a > program like Seti@home or Distributed.Net and keep your CPU busy all the > time.
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