Recently Exchange team has written an excellent article on Exchange processor and memory usage and how much of these resources should be used as many of the customers are willing to use extremely big hardware for Exchange.
Review the article at:
Ask the Perf Guy: How big is too BIG?
Read my favorites blogs:
Assigning File Share permissions using Power Shell
Disk Read Error when migrating virtual machine from one cluster to another
Designing a backup less Exchange 2010 Architecture
Step by step guide for upgrading Active Directory from Microsoft Windows 2008 R2 to Microsoft Windows Server 2012 R2
Microsoft Exchange 2010 Test cases
Microsoft Exchange 2013 and ADRMS Integration