486 Overdrive upgrade - Any experience?

[OVERKILL]

Did the old board have a fast enough fsb to jumper to a 233?

Yup, says it fully supports it, but I'm thinking there's something wrong with it.

 

[OVERKILL]

Socket 5 vs Socket 7?

Nope, both boards are Socket 7 (though the Biostar board that the Pentium 75 came out of was Socket 5). It lists the 233 MMX as supported in the manual, and I even flashed the latest BIOS, it simply will not work on that board.

 

[blufeb95]

Did the old board have a fast enough fsb to jumper to a 233?

Underclocking the CPU shouldn't have an effect on it, and I think a socket 7 CPU would generally run in a Socket 5 board, it's just not advisable long term as the higher core voltage can degrade the chip faster. Might just be the board lacked the microcode to allow it to run.

 

[blufeb95]

Nope, both boards are Socket 7 (though the Biostar board that the Pentium 75 came out of was Socket 5). It lists the 233 MMX as supported in the manual, and I even flashed the latest BIOS, it simply will not work on that board.

The only thing I could think is maybe there were multiple steppings of the Pentium MMX and even the latest BIOS doesn't have microcode support for later steppings of the Pentium MMX.

 

[OVERKILL]

The only thing I could think is maybe there were multiple steppings of the Pentium MMX and even the latest BIOS doesn't have microcode support for later steppings of the Pentium MMX.

I'd think if it supports a K6-III it should work with a Pentium MMX though. This is the board:
https://theretroweb.com/motherboards/s/jetway-j-tx98b#chips

 

[PandaBear]

Yup, says it fully supports it, but I'm thinking there's something wrong with it.

I remember back then there was some problem for people with 50Mhz FSB vs 66MHz FSB on the IO. Some IO works fine with 50MHz as is but the 66MHz FSB one has to step down to 33MHz, or was it the other way around they were ok at 33MHz but not at 50MHz.

In theory as long as you get your multiplier and bus correctly it should run, in the worst case slower.

Back then the CPUs weren't as picky about micro code, just as long as you have the clock speed correct it "should" boot. Everything was jumpered so you can calculate back and forth to see what is wrong.

 

[OVERKILL]

I remember back then there was some problem for people with 50Mhz FSB vs 66MHz FSB on the IO. Some IO works fine with 50MHz as is but the 66MHz FSB one has to step down to 33MHz, or was it the other way around they were ok at 33MHz but not at 50MHz.

In theory as long as you get your multiplier and bus correctly it should run, in the worst case slower.

Back then the CPUs weren't as picky about micro code, just as long as you have the clock speed correct it "should" boot. Everything was jumpered so you can calculate back and forth to see what is wrong.

I ended up just using a different board. The Jetway kept the P75 and the MMX went in a new board with AGP, where it rocks Duke Nukem 3D like a champion!

 

[JHZR2]

I'd think if it supports a K6-III it should work with a Pentium MMX though. This is the board:
https://theretroweb.com/motherboards/s/jetway-j-tx98b#chips

Yeah, K6-III with the L3 cache was newer than a 233 MMX.

I had an old compaq laptop that had a k6-II, which I purposely bought to upgrade to a K6-III. Always liked AMD.

 

[Jetronic]

This brings back memories, had a Pentium 200 that I ran on 2x112mhz, and had a K6-III after that.