Re: tlug-digest V1 #104

["A.Tomita,Jr." <Alberto@example.com>]

 > From: Craig Oda <craig@example.com>
 > Date: Thu, 4 Jan 1996 23:41:53 +0900 (JST)
 > Subject: Re: tlug-digest V1 #103 
 > 
 > On Thu, 4 Jan 1996, A.Tomita,Jr. wrote:
 > 
 > > There's another option: buy a Pentium 75 and overclock it to run at 90.
 > > It's a 3.3V chip, so overheating is not a problem, and the performance
 > > increase is significative. I did it in my machine at home, and it has been
 > > running fine for over a year now.
 > 
 > What is this really possible?  How can you do this?  By changing the
 > dip switch or jumper settings on a motherboard?  We build our
 > own machines in office, but we always set the processor speed
 > the same on the motherboard as on the chip.  How did you figure this
 > out?  Risking a CPU is kind of expensive if a person makes a mistake.
 > I call that gutsy.. :-)

Yes, there are jumpers that set the CPU external clock speed and the multiplier
(actually, it's a clock divider) for the internal clock. A same motherboard
accepts Pentiums 75/90/100/120, and in the manual there is a table showing the
jumper settings corresponding to each speed. I don't have it in hands right 
now, but it was something like:

	ext. clock	multiplier	int. clock
	  50 MHz	   1.5 x	   75 MHz
          50 MHz	   2.0 x	  100 MHz
	  60 MHz	   1.5 x	   90 MHz  	 
	  60 MHz	   2.0 x	  120 MHz

I had read in some Usenet newsgroup that it was possible, the only problem
been overheating the CPU. Tried until 100 MHz, but the machine started to
hang up; at 90 MHz it is stable.

-tomita.

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 Alberto Tomita Junior     URL=http://www.ishiilab.dnj.ynu.ac.jp/~Alberto 

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