CPUs for new databases

Hello,

What is the general view of performance CPU's nowadays when it comes to
PostgreSQL performance? Which CPU is the better choice, in regards to
RAM access-times, stream speed, cache synchronization etc. Which is the
better CPU given the limitation of using AMD64 (x86-64)?

We're getting ready to replace our (now) aging db servers with some
brand new with higher core count. The old ones are 4-socket dual-core
Opteron 8218's with 48GB RAM. Right now the disk-subsystem is not the
limiting factor so we're aiming for higher core-count and as well as
faster and more RAM. We're also moving into the territory of version 9.0
with streaming replication to be able to offload at least a part of the
read-only queries to the slave database. The connection count on the
database usually lies in the region of ~2500 connections and the
database is small enough that it can be kept entirely in RAM (dump is
about 2,5GB).

Regards,
Christian Elmerot