Square Chris said:
I own a HP Vectra VL420 with P4B-MX motherboard. As I am planning to
upgrade the CPU, can anyone advise whether this motherboard supports
Celeron D (compared with old Celeron, voltage ragne is mostly the same,
and the main differences are architecture [0.13 vs 0.09 nm] and FSB).
I prepare to run it @ 400MHz FSB.
Thanks in advance.
For best advice, see the Asus CPUsupport web page. It will
tell you which processors are designed to work. Sometimes
experimenters determine that additional processors work,
but the record with plugging Celeron D into things, results
in a lot of blank screens. There are reasons that this
happens.
http://support.asus.com/cpusupport/...px?type=1&name=P4B-MX&SLanguage=en-us&cache=1
If you go to developer.intel.com and download a datasheet for
a Celeron D processor, there are at least two additional pins
on the processor (these pins were not on the Northwood). One
is BOOTSELECT, and the other is the OPTIMIZED/COMPAT pin.
Older motherboards have a ground signal connected on the socket,
where the BOOTSELECT pin of the processor makes contact. If
the processor sees the ground signal on this pin, the processor
knows it is not supposed to run. That is a good reason for 90nm
processors to fail to work in older motherboards that are not
designed for them.
Asus did have a news release with a list of "Prescott ready"
motherboards, and those are the ones that would incorporate
design features to work with the pinout differences.
Apparently, the OPTIMIZED/COMPAT pin allows the processor to
sense what GTL reference level, and what output driver
characteristic impedance to use. Whether this pin does the
right thing when plugged into an old board, is a good question.
I think it more likely that BOOTSELECT will cause a failure,
than a wrong logic level on OPTIMIZED/COMPAT.
Your idea of "run it @ 400MHz FSB" means the core speed will
be scaled down, by the ratio of the normal FSB speed, to the
400MHz speed. This generally results in a great waste of
money, and a processor that is almost as slow as the one
you've got. The multiplier is locked on retail processors (only
ES engineering sample processors are unlocked in a way that
is useful to the end user). I would not recommend such a
down-clocking strategy, unless you were trying to make
a low power system.
Your best investment would be the 2.8GHz/FSB400/512KB cache
Northwood for $220, at the top of this page:
http://www.powerleap.com/Processors.jsp
While it is "one notch" above the highest speed listed on
the Asus site, it should still work as far as I know. And
being a Northwood, the pinout will be correct with no
surprises.
Paul
