It looks like the Radeon R3 iGP supports UHD over HDMI (4k). It's a line item in your mobo's specs
. However, I haven't seen whether it's using HDMI 2.0 or 1.4. The former allows for 4k/60Hz, the latter is 4k/24Hz.
No AMD chip can do HDMI 2.0 today, be it discrete gpu or integrated (soon to change presumably). 4096x2160@24Hz and 3840x2160@30Hz though should both be possible.
If the board had DP, theoretically 4k at 60 Hz could possibly work, though I wouldn't bet on it - I think Jaguar still has issues due to too small display buffers if you try to push the display outputs close to their limits (4k at 60Hz or 2 monitors with 4k@30Hz requires something like 1/6 of the total memory bandwidth just for display scanout, assuming ddr3-1600).
Oh, and for video the gpu can't decode 4k videos in hardware, and in software it's too slow (unless you're talking mpeg2 4k videos). But of course full hd videos upscaled to 4k output are working just fine.