On an IBM Intellistation M-Pro 6868
If I use two PIII Costa Rica SL448 they both run at 933 (as expected)
If I use two PIII Philipinees SL4BT they both run at 933 (as expected)
But:
If I use two PIII Malay QW39ES they both run at 600 and should be
running at 933
If I use two PIII Costa Rica QY02ES they both run at 600 and shoud be
running at 1G
I do have the latest BIOS for my mother board and there are NO jumper
settings or BIOS settings that will let you overide the multiplier etc.
Any ideas?
The letters "ES" on the end of the part number - are these
"Engineering Samples" ? They likely are multiplier unlocked
and boards of that era would have provided DIP switches or jumpers
to set the multiplier on an ES.
The 840 chipset is rated for 100 or 133MHz operation, and to
do 600, I guess they are doing 6x100 for some reason.
http://developer.intel.com/design/chipsets/mature/index.htm
The 6868 is described on the middle of this page:
http://www-06.ibm.com/jp/pc/intellistation/iszme02/iszme02s.html
If you are interested in hacking the hardware, the signals
on the SC242 that control the multiplier are mentioned here:
http://www.sandpile.org/post/msgs/10000034.htm
Pg. 33 of this dual processor 440BX based design, shows how
they played with the multiplier bits. Basically what that logic
is doing, is jamming a 4 bit pattern onto LINT0, LINT1, A20M,
and IGNNE, while reset is asserted. (This document will also
show you the pinout of the processor SC242 connectors.) I
would expect most motherboard makers would use simple
resistors (pull-ups or pull-downs), controlled by jumper
blocks, to do the same thing:
http://www.intel.com/design/chipsets/designex/BXDPDG10.PDF
Perhaps futher searching on the Internet, using those signal
names, will uncover an article on how to retrofit multiplier
controls on SC242 based motherboards.
If you look at this Pentium3 datasheet for SC242, you'll see
that Intel is careful not to explain how the multiplier is
set with those four signals. No mention of any funny business
with LINT0, LINT1, A20M, and IGNNE.
http://www.intel.com/design/pentiumiii/datashts/24445209.pdf
Now, the second mystery would be how an "ES" processor treats
the BSEL pins that set the bus frequency. It looks like your
QW39ES is not selecting 133MHz for some reason.
Motherboards like this one, offer the user some jumpers.
The BF3..BF0 set the multiplier. FS2..FS0 sets the bus clock
(and you'll notice it doesn't go all the way to 133MHz).
http://dlsvr03.asus.com/pub/ASUS/mb/slot1/440bx/p2b-d/p2bd(s)-106.pdf
Certain revisions of the P2B-DS motherboard, have a better
quality clock generator that goes to 150MHz. There is a mod
here, to access the higher frequencies on those revisions of
boards:
http://www.tipperlinne.com/p2b-ds150.htm
You might have a search around, and see if there is a better
motherboard to use in your machine.
Paul
