Intel Processors.

Hi guys,

As I am new to the world of servers I have a question regarding the Intel processor series on the PE rack servers.

Currently I see that the available generation of Intel Processors from the R320-R620 is the E5-24XX series.

Previously if I am not mistaken there were Intel ER-56XX series processors or something like that.

However I notice that when Intel released a new generation of processors, although number of cores available, L3 and L2 cache increase, processor speeds decrease or stay the same.

Would it be possible for somebody to explain this at a basic level and if possible link me to some really great reading material.

Thanks in advance,

Hosni