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scrathcyboy
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Can a 266 Athlon be run at 200 MHz?

In the higher Athlons, the C in the CPU code -- like AMD Athlon 1400AMS3C -- means 266 Mhz Bus capable.  
Can these CPUs be run at 200 MHz bus?  I have conflicting reports.  50% say they can, 50% say they cannot, they have to be run at 266, they will not work on a motherboard that will only take 200 MHz CPUs.  Anyone with any direct experience running the 266 Athlon on MBs that can only take 200 Mhz?

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scrathcyboy

8/22/2022 - Mon
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dbrunton

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willcomp

In my experience they will.  Multiplier is locked so it will run at about 1100MHz.  Core voltage is the same as other T-bird CPUs and you will not damage the CPU by installing it in a 100 (200) MHz FSB motherboard.

Main concern is whether motherboard will support a CPU with that high a clock multiplier.  Must be a board that can handle an 1100MHz CPU.
scrathcyboy

ASKER
The ABIT board has every setting you can imagine from 88 MHz up to 150 MHz -- but that does NOT mean it works with those CPUs.  I have found it does NOT work with Athlon XP, Athlon 133 or any other CPU other than the ones rated for 100 BUS.  Get this, it will work with an Athlon 1200 at 100 MHz bus, but it will NOT work with a DURON 1200 at 100 MHz bus, this is how quirky these motherboards are !!!
willcomp

Is there a BIOS upgrade that provides additional CPU support?
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zerathosthegreat

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scrathcyboy

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Obviously, if a 133 bus CPU is running at 100 instead of 133, it will be = speed/1.33333 = 1200 -> 900, 1400 ->1050.  That is not the point.  The point is, will it actually boot?  I put a DURON 1200 in this MB running at 200 Mhz and it would not boot.  I put an Althon XP in this MB and it would not boot.  I am not going to buy any more CPUs until I know they will boot in this ABIT MB, which only handles 100 bus, even though the CPU jumper switch is set to 133 -- apparently these ABIT BIOS programmers are real losers, 133 doesnt work, even tho the jumper says it does, it doesnt.
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willcomp

Errata: grissly = grossly
scrathcyboy

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"It may not accept a 1200MHz Duron due to BIOS.  Remember, it will ID the CPU type.  Definitely will not support an Athlon XP.  Should support any Athlon T-Bird that meets multipliers in BIOS with FSB set at 100MHz."

Yes, that is the conclusion I came to.  I tried 200/266 jumper, made no difference.  And the ABIT people state any athlon up to 1200, which is what they tested, and any duron up to 850, which is the limit they are testing at the time of FINAL bios update.

Hence these ABIT programmers evidently are ID-ing the CPU.  If it isnt on their list, the board fails to boot.  That I like a car refusing to start if it does not recognize the driver -- guaranteed failure thinking.  An intelligent programmer would check the bus speed, the CPU speed the core voltage and other params and then set that regardless of whether the CPU id was in their table or not.

I am upping points so I can assign a reasonable amount to everyone who contributed.  Thanks.
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