Actually its possible its your motherboard or your connection/cable, that IGPU does do 4K60 but you need either a HDMI 2.0 port and cable, or display port. Standard HDMI ports and standard HDMI cables that are not 2.0 certified can often do 4K30, but they dont have the bandwidth for 4K60. If i was you i would look into it, it could be that your motherboard supports 4K60, but you simply have a non spec HDMI cable without the needed bandwidth to transmit 4K60.
 
	https://ark.intel.com/content/www/us/en/ark/products/80806/intel-core-i7-4790-processor-8m-cache-up-to-4-00-ghz.html