As far as I know, the ThinkPad X1 Carbon Gen4 is only available with the HD Graphics 520. By the way, the Iris Graphics 550 can only be found in 28W U CPUs while the X1 Carbon uses 15W U CPUs.
Looking forward to your reviews of the fully maxed out x1 yoga OLED and x1 carbon. very promising! any indication when you will be able to get these into your lab?
Lenovo announced the new ThinkPad X1 Carbon, Yoga and Tablet at CES. The X1 family introduces innovative features like an OLED display and a modular tablet.