According to Intel website , hd graphics 4000 supports two external monitors
ports are available
But I not know the version of ports .Let intel users will reply to you with more details
The DisplayPort outputs of the 3rd generation Core processors with Intel HD Graphics 4000 support appear to be compliant with (only) DisplayPort specification 1.1a. Since MST support was not introduced until the DisplayPort 1.2 specification, I would conclude that, with only a single mDP connector, your laptop cannot support two external monitors. This jives with the User's Guide for the 1st gen Lenovo X1 Carbon laptop, which discusses only dual (internal + one external) monitor configurations.