[bonzini]

E3 is not a server SKU, it's meant for workstations and it's more similar to i7 than E5. It lacks various features including ECC RAM which, I suppose, is a no-starter for cloud hosting. Also some virtualization capabilities are missing, notably accelerated interrupt injection (APICv+posted interrupts).

[awill]

E3 does support ECC RAM. I'm running a Haswell Xeon E3-1225 with 16GB ECC RAM as my workstation.

[clhodapp]

I believe that the ability to use ECC RAM is actually the main differentiator between i7 and E3.

[compuguy]

I've seen E3's in low end servers like the Dell T20...