Performance problems on 4/8way Opteron (dualcore) HP DL585

Hi,

does anybody have expierence with this machine (4x 875 dual core Opteron 
CPUs)? We run RHEL 3.0, 32bit and under high load it is a drag. We 
mostly run memory demanding queries. Context switches are pretty much 
around 20.000 on the average, no cs spikes when we run many processes in 
parallel. Actually we only see two processes in running state! When 
there are only a few processes running context switches go much higher. 
At the moment we are much slower that with a 4way XEON box (DL580).

We are running 8.0.3 compiled with -mathlon flags.

Regards,

Dirk