[Beowulf] Re: Beowulf Digest, Vol 10, Issue 16

Mark Hahn hahn at physics.mcmaster.ca
Mon Dec 13 17:05:23 PST 2004

> >> I believe the socket 754 and 939 Athlon 64s do not support ECC, while
> >> the socket 940 Athlon 64 and Opteron do.
> >
> It's hard to tell what the 754 boards support since many say they
> will _accept_ ECC memory but they don't say that they can actually
> _use_ it.

all K8's support ECC - AMD definitely does not disable ECC on some chips.
I just checked the s754 functional spec, and it certainly supports ECC.

it's conceivable that MB vendors are such twits that they'd fail to 
detect ECC dimms and enable ECC in the bios.  it's even possible they'd
be such idiots as to fail to connect memcheck pins to the dimm slots.

> If you want ECC in Opterons, you need socket 940
> Socket 939 supports 128 bit memory path, no ECC
> Socket 754 supports 64 bit memory path, no ECC
> Some may accept it, but will NOT be able to use it.

perhaps; I'm guessing that *ANY* lack of ECC is strictly due 
to the bios-writer's choice.  perhaps linuxbios is salvation here.

it would actually be amusing to try doing this from within linux,
since reconfiguring the memory controller is probably doable 
via setpci or wrmsr.  if you try, please backup beforehand ;)

regards, mark hahn.

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