I got bit by a bad jumper too....
I added jumper 'blocks' (salvaged from a dead HD) to a Cobalt
RAQ 3i. Turns out one of the jumpers I put on the voltage selection
pins was bad... and I overvolted the CPU and fried it... thankfully
I hadn't put in the K6-2+ at that point yet !
Wouldn't it be more sensible if the voltage selection circuit was
designed so that if a particular jumper was open it always gave a lower
output voltage tyhan if that jumper was closed (all other jumpers being
set the same). Then an open jumper would not fry anything.
But then it's my bitter experience that good design and PC hardware do
not go together...
This story has also convinced me to carry on checking all voltage outputs
with a meter before connecting anything to them. In this case, to check
the CPU power voltages _at the pins of the CPU socket_ before plugging
said chip in.
-tony