hoang@rex.cs.tulane.edu (Dzung Hoang) (12/22/89)
Thank you to the gentleman who sent me the necessary pinout info
for the 80287. I connected pin 39 (clock multiplier) to 5V and that did
it, actually over did it. The 287 is now running at 12MHz, a little over
the 10Mhz the chip is rated for and above the CPU's 10Mhz.
Is running the 287 above its rated speed harmful or dangerous? I know
that the chip will probably heat up more, but will it affect anything else
in the computer? I do have a heat sink that I can put on the chip to help
cool it, but I don't how to attach the heat sink. Is there a readily
available heat-conductive glue that I can use for this job?
Replies to the above questions will be appreciated.
Dzung Hoang
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-----------------------------------------------------------------------------henry@utzoo.uucp (Henry Spencer) (12/29/89)
In article <1716@rex.cs.tulane.edu> hoang@rex.cs.tulane.edu (Dzung Hoang) writes: >...The 287 is now running at 12MHz, a little over >the 10Mhz the chip is rated for and above the CPU's 10Mhz. > > Is running the 287 above its rated speed harmful or dangerous? ... It will probably increase power consumption and heat dissipation, but probably not enough to cause trouble unless the design was marginal to start with (which is possible...). More to the point, though, is the question of whether you can trust the answers you get out of the chip. The chips marked "10MHz" are generally the ones that flunked the tests at 12MHz (or whatever the next speed grade is). Now, those tests are a bit conservative, and depending on things like supply voltage and temperature, you may not have trouble. Then again, you might. Worse, if the chip is right on the edge, then when something changes a little bit -- room temperature, power-line voltage, component aging, phase of the Moon -- you could start getting intermittent failures. I wouldn't trust it for anything crucial. -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1989: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu