"David M. Moore" <[EMAIL PROTECTED]> writes
>I now have this 486 machine doing the factoring that was
>being done by the P120. Generally, it is taking almost two weeks per
>exponent.
You could upgrade to a P120 very cheaply. In England the going rate for
a P120 CPU is about 20.00GBP and 1.00GBP for a suitable motherboard. In
the US I should imagine it's the same numbers in $s. People are almost
giving them away.
>Therefore, my question is even with this two week time, is the 486
>machine doing "useful work" for GIMPS, or is it merely heating up the
>CPU? I ask this because in a couple or three weeks I may have access
>to a quantity (30 to 75) of 486DX-50 machines. If these machines can
>contribute useful work to GIMPS, I will happily give them each a mouthful
>of exponents to factor :-)
It's a nice thought, but you really need cheap electricity to make it
work. I found that a typical 486DX-33 (I don't have a -50 to hand) uses
about 21 Watts, and that's without an HDD. Multiply by 75 and it could
start to get expensive, although in the winter months you would make a
saving on your heating costs.
By contrast an AMD/K6/2-400 on a basic motherboard (no sound, no video)
and no HDD draws only about 35 Watts.
--
Tony
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