You need some serious grunt backing it up depending what your doing.
I do focus stacking macro photo's occasionally with an occasional go-pro video edit.
The display quality of the 4k is good for just viewing but its the machine its fitted to that makes the difference to working with images and video.
When I stack 50 macro photo's its the ram and the processor that gets the hell kicked out of it, the same with video.
24GB ram i7 will run happily at 100% for 5-10mins converting a 30min go-pro video or dealing with a hefty focus stack.
The games machines will have the cooling sorted for you. And the amount of ram will help. As will a SSD.
If the machine is just for viewing the processor and ram on the MB isn't much of an issue. You need a reasonable sized ram on the GPU 2/3Gb and a SSD to keep the data transfer up. And make sure the cooling system is up to it.
Also as well if its for photography get a colour calibrator for the system. Other wise your going to get issues with people claiming the colour doesn't look right. 9/10 its their systems which are out but the 1/10 that calibrate their own will bitch like hell knowing they are right.