At 09:43 07/10/00, Roberto Safora wrote:
>What would be the best frequency option for a PIII FC-PGA 533 running on a
>66/100 FSB motherboard?
>Any experience in running fc-pga 533 as a 550(5.5 x 100)
>My mobo doesnt have, (expressed) a 133 mhz fsb


Hi Roberto

I think that your FC-PGA Pentium III 533 was designed to
be run with a 133 MHz FSB. Your problem is that Intel has
"locked" the bus multiplier in all their present processors.
So no matter what frequency you run your PIII 533, it will
use a multiplier of 4.

It was designed to be run at 4 X 133 (which equals 533)
but if you run it at 100 FSB, the speed you will get is
4 X 100. (This would yield a disappointing 400 MHz.)

Even if you set the jumpers on your motherboard for a
multiplier of 5.5 (or tell your BIOS to use 5.5), the
processor will ignore this and run internally with the
multiplier of 4. It is "hard wired" to use this multiplier
and I don't think there is any way to get around this.

If you had bought a 533 MHz Celeron (designed to run at
8 X 66 MHz) you *might* have been able to get it to work
at 8 X 100 MHz. (I read that many people have done this
successfully with good processor cooling.) Note that the
multiplier for the Celeron 533 is also fixed, in this
case at 8. (Also note that the 533 Celeron is not necessarily
a FC-PGA processor.)

Getting back to your FC-PGA Pentium III, there is another
thing you must worry about. Can your motherboard supply
the lower voltage for the FC-PGA processor? Older
Pentium III and Celeron processors (as well as Pentium II)
required 2.00 volts for the core voltage. The newer
Pentium III processors require about 1.65 volts and many
older motherboards cannot supply this.

I assume that you have a slot one version of the Pentium III.
(This is also called SECC2.) If you instead have a 370 pin
Pentium III chip meant for a socket, not all slotket cards
(cards that adapt a 370 pin chip to fit into a "slot one"
motherboard) work with Coppermine (FC-PGA) processors. While
they both fit in the same socket, the 370 pins on Coppermines
do not have the same functions as the 370 pins on older
Celerons...for which many slotkets were designed. Be sure
that you have a slot one (or SECC2) Pentium III or that you
have a "Coppermine ready" slotket.

Regards,
Bill

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