Advanced Micro Devices Inc (AMD)

[chipguy]

SZ, I ask you - how can Opteron be slower than Athlon?

Glad you asked. Opteron is a 64 bit machine that runs 32 bit code very well. You might want to study the circumstances around the transition from 286 to 386, 16/32 bit respectively.

Few if any 32 bit programs by definition are optimized for Opteron hence the '32 bit'. Not that they couldn't take advantage of the flat memory adressing. But, that would be superflous effort, since 64 bit applications will have that advantage and much more.

Hold on now, this flip-flopping has me confused. I thought K8
was so great because of its super duper performance on 32 bit
code. Now that is shown to trail P4 and even Athlon the story
changes to oh no, it needs 64 bit software to show its stuff.
Someone on Aces's showed that the 64 bit SETI client app was 9%
slower than a generic 32 bit client on Opteron. The appologists
then say it is the wrong kind of app for 64 bits (doesn't use
enough registers, or SSE yada yada yada). Well it sure the heck
is the right kind of app for IPF style 64 bits because an old
900 MHz McKinley ripped the Opteron a new one on SETI, more
than twice as fast as Opteron running either 32 or 64 bit code.
Even whipping boy Itanium/Merced was about a third faster.