I've seen a similar behaviour, but not such a big swing. The P4s Xeons 
were more than 40% slower than the Opterons. The current generation of 
Xeons however do bettter by 10% over the Opterons. Of course you need to 
also weigh in the cost of the chips, but looking at the system as a whole 
that isn't as large an effect.

On Wed, 26 Sep 2007, Miles O'Neal wrote:

> Troy Dawson said...
>
> |It really comes down to your application.  If possible, try it on two
> |comparable CPU setups, one AMD and one Intel.  I've seen some wildly lopsided
> |tests, try to at least give them the same amount of memory and the same disks.
> |Then run your application on it, and see which is faster.
> |
> |That's how I decided I like the Opteron.  On my tests (recompiling rpm's) the
> |Opteron beat the Xeon.  But I saw other people with the exact same setup, and
> |for them the Xeon beat the Opteron.  It all came down to the application.
>
> And that can change over time.  For years
> we bought only AMD-based systems, because
> most of our apps consistently ran better
> on them.  Then we found a couple that were
> decidely better on INtel.  When we tested
> equivalent servers for the last set of
> compute farm systems, Intel won hands down.
>
> -Miles
>

--
  /------------------------------------+-------------------------\
|Stephen J. Gowdy, SLAC               | CERN     Office: 32-2-A22|
|http://www.slac.stanford.edu/~gowdy/ | CH-1211 Geneva 23        |
|                                     | Switzerland              |
|EMail: [log in to unmask]       | Tel: +41 22 767 5840     |
  \------------------------------------+-------------------------/