🚀 go-pugleaf

In article <1993Jan6.162636.9927@ac.dal.ca>, francis@ac.dal.ca writes:
|> I have a 486DX/33MHz system, and I have been told by the manufacturer that
|> the motherboard is upgradeable to 50MHz by plugging in a new crystal and CPU.
|> 
|> Question:  	Is it possible to plug in (say) a 40MHz or even a 50MHz crystal
|> 		into the board *without* replacing the old (33MHz) CPU? 
|> If so, is there a performance improvement or will the 486DX 33MHz chip just
|> burn itself out, ie, has it been internally hardwired for the specified clock
   ^^^^^^^^^^^^^^^                             ^^^^^^^^^
burn out: veeeery probably.
hardwired: not directly. The chip's power consumption does not
allow for higher frequencies. In priciple, the shorter the switching 
times of the CMOS transistors, the less the power consumption will
be (which occurs mainly during the hi-to-lo and vv. transition). 
Switching times are a random result in the manufacturing process,
so that all chips from 33 to 50 MHz are born from the same fab. They
are selected for frequencies thereafter. Intel shot the bird: When
having problems with their 486DX at higher frequencies, thus producing
many chips that wouldn't work even at 25 MHz, they un-bonded the co-pro
and named the result 486SX-20. 
  
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In comp.os.msdos.misc (subj: Run 33MHz CPU at 40/50MHz?), francis@ac.dal.ca writes:
> I have a 486DX/33MHz system, and I have been told by the manufacturer that
> the motherboard is upgradeable to 50MHz by plugging in a new crystal and CPU.
> 
> Question:    Is it possible to plug in (say) a 40MHz or even a 50MHz crystal
>     into the board *without* replacing the old (33MHz) CPU? 
> If so, is there a performance improvement or will the 486DX 33MHz chip just
> burn itself out, ie, has it been internally hardwired for the specified clock
> frequency of 33MHz?  I would like to hear from anyone who has attempted this
> (with/without success).

Most likely results:
      Flakey processor.  A 33MHz-rated chip is designed to run at 33MHz
      under worst-case conditions.  So, if you run it faster:
         - it may or may not work, even under 'optimum' conditions
         - it almost certainly will not work as the chip heats up.
      Luckily, I believe the innards of the chip are CMOS, so if the chip
      overheats it won't start thermal run-away and "catch fire".  However
      running the chip too hot will probably destroy it over time as 
      metal migration and other nastys occur.

   Suggestion: Don't do this.  Even if it seems to work for a while, you
   may be corrupting memory and your disk!

                        - Bruce Erickson
                        Hewlett Packard
                        bae@col.hp.com