[Beowulf] Opteron downrates DDR400 to DDR333 performance?

[Greg Lindahl]

On Sat, Feb 04, 2006 at 12:51:46PM -0500, Mark Hahn wrote:

> well, FBdimms maintain a high clock, but stretch latency quite a bit as 
> you add devices.  and that's some distance off, I think - rumor has it 
> that AMD is close to shipping DDR2 support.

FBdimms are great for having a of devices on a single channel and they
reduce the pin count which allows more channels, but they're bad for latency.

I don't think anyone outside of AMD has any idea when Rev F Opterons
will ship -- those are the ones with DDR2 support. However there is a
new trick with Rev E Opterons that improves memory performance, if you
look at recent SPEC submissions you'll note a large improvement (~
10%, if I recall correctly).

-- greg