Was originally gonna replace the FSB frequency and multiplier dipswitches with pinheaders on my Gigabyte GA-586HX board, to be able to connect external FSB/multiplier switches, but turned out there are revisions of the same board where you set those with jumpers. The jumper headers were there on my board revision (1.53) too, just not populated with pins. Great! Installed pin headers, and kept the dipswitch rack. If I ever want to go back to using the dipswitches, I just need to unplug the external switches. No replacement needed. The four dipswitches are set to OFF (open) when using the external switches, electrically it's the same thing as if they weren't there.
A few pics if anyone is interested:
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Guess everyone here already seen the innards of a computer and jumper headers a million times, so didn't bother with that. Here's the raw material for the switch panel. A few SPDT switches, an IDE cable, and a 0.10" C/C connector I've salvaged somewhere.
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Cut out smaller connectors from the salvaged one, fitting the new pin headers. Prepared leads from the IDE cable, and soldered everything together, some heat shrink tube to cover the solders as a finishing touch. Drilled out holes in a spare white front cover (kept the original one untouched), and tested that everything fitted together.
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Printed out a table of all possible combinations and corresponding FSB/CPU speeds, and markings for the switches.
It works great! Even though it doesn't match the flexibility and convenience of a K6-II/III-system, it's not that far from it. Flicking a few switches and disabling caches in BIOS ain't all that painful either 😀
Also installed pins on the USB header. Wonder why it wasn't populated? Perhaps someone back then thought noone would care about USB? Or was USB 1.0 (which I assume it is on an old 430HX board) obsolete already when the board went into production?
Removed the jumper wire on the Cyrix/Intel selection header too while I was at it, and installed a pinheader with a regular jumper there instead. Could be fun experimenting with if I ever get hold of a Cyrix CPU.