Fastest CPU for Intel E7525-based motherboard?

[MIDIman]

We bought a Dell Precision 670 a while back and are thinking of upgrading. What is the nomenclature for CPUs that this E7525-based motherboard can take? Can I upgrade it with dual-core Xeons?

Looking at this...it looks like it will only take socket 604 up to 3.6ghz.

 

[Aluvus]

Dell sells it with up to a 3.8 GHz single-core Xeon (not sure which core that is; it smells like Irwindale, which is not 7xxx series) or a dual-core 2.8 GHz chip (which is almost certainly a Paxville, the dual-core bigger brother of Irwindale). It would have to be Socket 604. Those are the only Xeons I'm aware of that support EM64T and have the right L2 cache and FSB.