SK8N woes

[Peter Wemm]

On Saturday 13 November 2004 12:21 am, Ruslan Ermilov wrote:
> On Fri, Nov 12, 2004 at 11:58:01PM -0800, David G. Lawrence wrote:
> > > On Sat, Nov 13, 2004 at 12:25:48AM +0100, Gert Cuykens wrote:
> > > > no registered memory works ONLY yes ONLY with registered memory
> > >
> > > What do you mean?  This memory type (please read below) is
> > > explicitly listed in section 2.4.3 (Qualified Vendor List)
> > > of the SK8N manual as "memory modules that have been tested
> > > and qualified for use with this motherboard".
> > >
> > > > > - Memory: Kingston KVR333X72C25/512 (this is in the list
> >
> >                                   ^R
> >
> >    Are you sure that it doesn't have an "R" before the "C" in the
> > above part number?
>
> I have modules without the "R" letter, and the manual lists them
> with "R".  I assume "R" means "registered", so that must explain
> it.  THANKS A LOT!!!

Yes, the R is registered.  For the opteron and socket 940 athlon64's, 
you need registered dimms.  For socket 754 and 939 athlon64's, you need 
unregistered dimms. 

Registered dimms are slightly slower overall because they add an extra 
half clock latency for the buffers to sample and latch the data.  But 
it allows much longer trace lengths between the cpu and dimms and 
allows more dimm sockets.

FWIW ECC is just extra bits on the dimms (72 bit vs 64 bit), it
is unrelated to whether it is registered or not.  I use *un*registered 
ECC dimms on my socket 754 motherboards.
-- 
Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5