This article from Tom's Hardware Guide is about the new Pentiums, but it mentions in passing that the new Opterons have SSE3.
<a href="http://www.tomshardware.com/cpu/20050221/prescott-01.html">Prescott Reworked: The P4 600 Series and Extreme Edition 3.73 GHz</a>

With our current compile, with the Intel compiler, would it use SSE3 on an Opteron?

I think Intel chips would still have the advantage with hyper threading. But if your really anti-Intel and the heat they produce, could you get a Opteron or multi-Opteron system and get similar results? Not that I could afford such a thing anyway, but hypothetically. . .

&gt; I think Intel chips would still have the advantage with hyper threading. But
&gt; if your really anti-Intel and the heat they produce, could you get a Opteron
&gt; or multi-Opteron system and get similar results? Not that I could afford such
&gt; a thing anyway, but hypothetically. . .
&gt;
It's hard to say, but the current compiler CPDN is using penalizes Athlon64s on SSE2 and I can't see that changing if using SSE3 and Opterons. However, later versions of the Intel compiler supposedly don't penalize Athlon64s. We had a discussion about the compiler used back in August and September with a number of posts.