Haven't you checked out this review yet? It's quite old though.
<A HREF="http://www.aceshardware.com/read.jsp?id=60000268" target="_new">nVENTIV Mach II: The Athlon 64 FX at 2.8 GHz</A>
Btw, we can deffinetely expect faster performance from the FX-57 (2.8GHz) when it will be introduced, since it will be on S939, 90nm, using a new core stepping, faster hypertransport, and non-ECC DDR memory modules. So, if these two articles are any indication about what we can expect by the end of this year, then AMD seems to be in a very good position, if they manage to ramp up 90nm production without any problems of course.