🚀 go-pugleaf

William Taylor <wwtaylor@ix.netcom.com> wrote:
>In article <4bhhpt$cg9@aladdin.iii.org.tw> Kim Monson,
>KMonson@cyberstation.net writes:
>>Intel's Zappa MB seems to only support up to 133 MHz. However, there is talk 
>>of future Pentium overdrive chips like today's 486 DX4s that run faster 
>>within the CPU, but run at the system clock rate externally. Apparently this 
>>would work in a board such as the Zappa.
>
>I'm confused. Pentium's are using a clock multiplier. It seems to me that
>all they need is the correct external clock from the motherboard: 50, 60,
>66Mhz. The cpu then takes that and multiplies it to get the correct
>internal speed. 
>
>Why can't you plug a P5/166 chip in a P5/100 board (66Mhz) and have it
>run? The only problem I can think of is the BIOS. 
>
>Please explain,
>
>WT

For the clock frequency, the P54C/166 runs at 66MHz externally as well. 
However, you also need to support the voltage spec. The P54C/166 will run 
at a different voltage from P54C/100 which will make some motherboards, 
espcially the older ones, not able to support variable CPU voltage to fail 
to use P54C/166.
That is why intel has the Pentium Overdrive plan which will make a faster 
Pentium to be compatiable with old motherboards. Just like the 486DX4, you 
cannot put a 486DX4 on a motherboard that supports 5V only. Instead, you 
put the 486 Overdrive into the 5V socket.

Joe