by Gibsaw on Sun Oct 09, 2016 10:08 am
ok... On Mobo's of this vintage, there's usually two sets of jumpers.
A base clock frequency one, which often has two jumpers and three valid settings - Usually 25MHz /30MHz / 33MHz / undefined. This is the speed the PCI bus ran at, and the proc's external BUS to cache and RAM ran at twice this. (Also it is banked and the bus to RAM is 64 bits wide)
A multiplier, which is also usually two jumpers and can be set to
- 1 (50/60/66)
- 1.5 (75/90/100)
- 2 (100/120/133)
- undefined.
(I've also seen Mobos with 3 positions for the base freq instead of two jumpers.)
At the time these mobo's were being put out, a lot of the basic P54C boards didn't even dream of higher base freq's but usually a 2x multiplier was doable, and in fact the interpretation is done by the processor anyway. (they correlate to pins directly on the pentium and the processor will interpret their value.)
Most early P54C's used the same interpretation until they started reusing settings for higher multipliers, hence you put in a P133 and it has decided to run at 100.
You won't really hurt the proc by trying a few seconds at other multipliers. It will interpret the setting to a valid setting for it's generation. Even accidentally altering the clock freq, you'll be likely to take it down as it's already set to 33MHz.
Main thing is to find the right jumpers. They're usually in a block right by the processor, but of course you don't want to accidentally alter ones that affect voltage.
Can you post a wider pic of the board, showing the chipset? Perhaps the model number of the HP box from the bottom?
"dsakey" on trademe. Apple II's are my thing.