[giantrobot]

I've got an i5 530 in a server in my lab. Since it runs idle for long periods it isn't very power hungry. It is also beefy enough for a lot of different loads.

I've found pretty much everything since the Core 2 Duo to be more than enough of for "server" tasks.

[Arrath]

Likewise, my i7 920 continues kicking and handling most any random task I throw at it. I retired it as my daily driver in late 2018, but I sure got my mileage out of that thing.