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First post, by Blitz_25

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I have a question regarding Cyrix MII 233GP. I have one of those that is rated at 75Mhz at 2.5x multi thus running at 189mhz effective.
Now my socket 7 motherboard does not support 75mhz (only 66.6, 83.3, 90, 95, 100/ MHz) so I'm running CPU at 66.6Mhz and 3x multi giving me a slight overclock of 200Mhz.
Would it be OK for CPU if I set base to 95Mhz and multi to 2x or will the 95Mhz base clock be to much for CPU.

I've searched the web for info and got more questions than answers. All I gathered is that Cyrix made same PR rated MII CPU's that were rated to run at either base 66,6, 75, 83,3 95, or 100 /MHz but are those same PR rated CPU's internally same even though they are rated to run at different base clock and multipliers?

Last edited by Stiletto on 2021-11-24, 22:45. Edited 1 time in total.

Reply 1 of 6, by Anonymous Coward

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Your 233GP was the second slowest in the MII lineup. Actually I'm not even sure if MII 200GP was an official release, it's very rare. In any case the overclocking potential for your CPU should be high. Running at 2x95 isn't really overclocking the CPU, and 95MHz bus shouldn't cause any damage.

There was a die shrink for the MII. The later batch ran at 2.2V while the older ones ran at 2.9V. Yours is almost certainly 2.9V. The slowest 2.2V MII I've seen so far is the 300GP. The lower voltage parts should be better overclocking potential.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 2 of 6, by Blitz_25

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Thnx for inf. I've "plunged in to water" and selected 2x 100mhz (200mhz effective) and so far averything is runing cool and stabile.
Funny is even thoug CPU is running at effective 200mhz (2x 100) same as before (3x 66,6) now it gets detected as PR350 and not PR233.

Reply 3 of 6, by Garrett W

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Blitz_25 wrote on 2021-11-25, 11:49:

Funny is even thoug CPU is running at effective 200mhz (2x 100) same as before (3x 66,6) now it gets detected as PR350 and not PR233.

Cyrix got a bit desperate by the end there with the PR notation. I have one of those die shrunk MII (they are sometimes called MIIv) at 285 MHz sold as PR400 or rather 400GP. It runs happily at 300MHz with a 100MHz FSB and gets recognized as 433GP. By this point, I'm unsure what 433 is supposed to mean exactly, what were they comparing it against? Perhaps a hypothetical Pentium MMX running at 433MHz, barring FPU performance of course. I'm not entirely sure that's the case either. I've heard rumors about a supposed 466GP, but I'm unsure at what frequency this would have run at.

Reply 4 of 6, by Anonymous Coward

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The 'v' in MIIv does not indicate a die shrink. You can find many MIIv with the older 2.9v core. The 'v' stands for VIA, so any chip with a 'v' in the name indicates it was produced (or sold) after VIA bought Cyrix from Natsemi.

I think there was a press release by National Semiconductor for a PR466, PR500 and PR533, but those chips never made it to market. Following those, I believe a new core was to be introduced which had a beefed up FPU and probably integrated L2 cache. Instead VIA bought them and sold crappy Winchips under the Cyrix name.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 5 of 6, by Garrett W

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Huh, the more you know. Anyway, mine's the 2.2V version, so that's a good indicator it's a die shrink.

Jedi and Gobi seemed interesting. I forget, did VIA ever market any processors that were designed by the Cyrix team? I quite like the later, Centaur-developed, Nehemiah C3, they are plenty fast for my needs and very flexible for slowing down.

Reply 6 of 6, by Sphere478

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Blitz_25 wrote on 2021-11-23, 08:55:
I have a question regarding Cyrix MII 233GP. I have one of those that is rated at 75Mhz at 2.5x multi thus running at 189mhz e […]
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I have a question regarding Cyrix MII 233GP. I have one of those that is rated at 75Mhz at 2.5x multi thus running at 189mhz effective.
Now my socket 7 motherboard does not support 75mhz (only 66.6, 83.3, 90, 95, 100/ MHz) so I'm running CPU at 66.6Mhz and 3x multi giving me a slight overclock of 200Mhz.
Would it be OK for CPU if I set base to 95Mhz and multi to 2x or will the 95Mhz base clock be to much for CPU.

I've searched the web for info and got more questions than answers. All I gathered is that Cyrix made same PR rated MII CPU's that were rated to run at either base 66,6, 75, 83,3 95, or 100 /MHz but are those same PR rated CPU's internally same even though they are rated to run at different base clock and multipliers?

*usually* though not always you can set the bus frequency to whatever the motherboard supports and the cpu to whatever the cpu supports, so yeah, you can probably set it to whatever gives you near a stock core speed.

By supports I mean whatever the board is capable of being stable at. As not all settings always are stable.

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