How to Surface book to run 2 -4K monitors

[ToastyX]

That's weird that the Samsung U28590D doesn't offer 30 Hz with DisplayPort. One way around that is with an EDID override, but I don't think there's a way to do that with a Surface Book because it has an Intel GPU. The other way is to use Intel's control panel to add a custom resolution, but I don't think the driver for the Surface Book includes the Intel control panel. You can try downloading the official Intel driver (get the .zip version) and installing it manually through the Device Manager: https://downloadcenter.intel.com/download/25951/

The other option is to use HDMI for both monitors. You should be able to get 3840x2160 @ 30 Hz with HDMI, but you need to use active adapters.