Differentiating Coppermine Cel and P3, both 100 FSB

[ImJustaHobbiest]

How does a motherboard differentiate between a Coppermine 100 FSB Celeron and
a Coppermine 100 FSB Pentium-3? I have a PcChips M755 motherboard and it's supposed
to support P3s with 100 FSB. If I put in the Coppermine Cel, the BIOS recognizes the CPU
as a Cel rather than P3 and consequently tries to set the bus and other things to 66 MHz
(as for older non-Coppermine Cels). The two CPUs have the same core voltage, ID strings
(068A) and bsel[1:0]=01 (for 100 FSB). As far as I know, the Cel is just a crippled P3 with
128k L2 cache, so there shouldn't be any external indicators. I just want the Cel to be seen
as a 100 FSB P3 so all the board components would be initialized properly.

Thanks for any enlightenment.


The Intel info for Cel:

sSpec Number SL5XU
Processor Frequency 1.10 GHz
CPUID String 068A
Package Type FC-PGA
Core Voltage 1.75V
Bus Speed 100 MHz
Thermal Design Power 33.0W
Core Stepping cD0
Max Junction Temp 77°C
L2 Cache Size 128K
Die Size 0.18 micron
L2 Cache Speed 1.10 GHz
ECC/non-ECC ECC
Bus/Core Ratio 11.0
Boxed/OEM Processor? OEM
Product Order Code RB80526RY005128

For P3:

sSpec Number SL5QW
Processor Frequency 1.10 GHz
CPUID String 068A
Package Type FC-PGA
Core Voltage 1.75V
Bus Speed 100 MHz
Thermal Design Power 33.0W
Core Stepping cD0
Max Junction Temp 77°C
L2 Cache Size 256K
Die Size 0.18 micron
L2 Cache Speed 1.10 GHz
ECC/non-ECC ECC
Bus/Core Ratio 11
Boxed/OEM Processor? OEM
Product Order Code RB80526PY005256

 

[Spikesoldier]

the cpu's micro code/device id tells the hardware what it is.

maybe there is a jumper or bios setting that is holding you back?

also the in addition to half of the L2 cache, it is only 4-way associative instead of 8-way on the p3.

 

[afzan]

did you try updating the bios?

 

[ImJustaHobbiest]

If by device id, you mean the CPUID String, then you will notice that both have 068A.
Most motherboards, including the M755, detects CPUs using this string, in conjunction
with the bsel[1:0] pins that selects FSB speed. Hence, if a board supports the P3
with ID=068A and bsel[1:0]=01, then it must support the Cel with same, unless there
is some other distinction. The spec for the M755 claims to support all P3s from
500 to 1130 MHz, at 100 or 133 FSB, and all Cels from 300 to 700 MHz, at 66 FSB.
One would think that this includes the P3 at 1100 MHz at 100 FSB, which by implication
includes the Cel at 1100 MHz at 100 FSB. However, there is a chance that it doesn't
really support P3s at 100 FSB (but only 133) above a certain frequency.

PcChips is pretty bad about BIOS upgrading, since it's a bulk OEM motherboard vendor.
I have the latest BIOS. The hardware, which uses the Sis630E chipset, should be able
to handle the 1100 MHz at 100 FSB, since many other motherboards using the same
chipset explicitly states support for the Coppermine Cels, so it's probably all because
of outdated BIOS firmware.

Oh, well...