I've had headache and/or visual fatigue with an i5-6500 system (Lenovo) using its 530 Intel integrated graphics with DisplayPort, both with the Integrated 530 driver enabled or disabled, although the symptoms are usually lower when the driver is disabled. The system came preconfigured with Windows 10 but I've also installed Win 7 and Win 8.1 on it (Win 7 installation was a bit more challenging given the need to install drivers separately, such as for USB 3.0). I've tried this sytem with several UHD monitors including Samsung UR55, Samsung UJ59, and LG 32UL500. I've also tried it with a PCI graphics card (K420, GeForce710, and Radeon 5450) but not with all of the above monitors but it still provided symptoms with whatever UHD monitor I tried it with.
This Lenovo system is more comfortable if I connect it with one of my older (2011 or so) LED displays.