The current form is "AMT", but was preceeded by "MEBx" in earlier chips. I first came across it in a Dell OptiPlex-755 box I was setting up. The box was unreliable in shutting off and rebooting, and "MEBx" was the culprit:

http://rtr.ca/optiplex755/

Here is Wikipedia's article on the current form, "AMT":

https://en.wikipedia.org/wiki/Intel_Active_Management_Technology