Take any two: motherboard performance, compatibility, value

[Josip Loncaric]

Hello,

since last year, choosing a motherboard for Beowulf applications has
gotten much more complicated.  Intel has locked itself into a bizarre
RDRAM corner, VIA has only chipsets which tolerate but do not use ECC,
AMD still does not have a successor for its 750 chipset, and it may be
2001 before motherboard market offers attractive choices.

Our needs are fairly basic:

(1) K7 or P3 processor in a compact package (->dual CPU)
(2) lots of fast RAM using ECC
(3) Linux compatibility
(4) commodity pricing

The K7 route offers only single CPU systems.  To use PC133 RAM, one must
pick KX133 chipset, which does not perform ECC (it only tolerates such
memory modules).  No SMP, no ECC yet: K7 is out for now. 

The P3 route is also problematic.  Intel's recent dual CPU chipsets are
i820 and i840, but they insist on RDRAM which (today) costs 3-4 times
more than SDRAM, without providing a consistent benefit.  RDRAM is *not*
an option for us.  However, SDRAM on i820 motherboards requires MTH chip
(now recalled because noise causes random reboots), while i840
motherboards need the MRH-S chip which is now also discontinued by Intel
(incorrect ECC operation was reported).  Since RDRAM price/performance
is so poor and i8x0 chipsets do not work correctly with SDRAM, both i8x0
chipsets are out.  

This leaves VIA Apollo Pro 133A chipset (used by Tyan Tiger 133 S1834),
but this chipset does not use ECC.  About the only remaining option are
ServerWorks chipsets (used by Supermicro Super 370DLE), but I do not
know if anyone has made them work with Linux.

So we are back to square one, i.e. 440BX SMP motherboards and PC100
RAM.  This is Not Good.  High RAM bandwidth is essential, particularly
on dual P3/800 machines (faster clock, smaller cache)...

BTW, I see that ECC corrects about one single bit error per month in
12GB of RAM.  Our total system will have close to 40GB, so errors could
pop up weekly, which is why we need ECC.  

Sincerely,
Josip


-- 
Dr. Josip Loncaric, Senior Staff Scientist        mailto:josip at icase.edu
ICASE, Mail Stop 132C           PGP key at http://www.icase.edu./~josip/
NASA Langley Research Center             mailto:j.loncaric at larc.nasa.gov
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