When trying to use my discrete video card whole system freezes after couple of
seconds and doesn't react on anything. I've tried to have a delayed killall -9
running in the background like "sleep 60 && killall -9 glmark2 &" but it seems
to be never run or having no effect. Only hard reset helps. 

Have Intel HD4000 + muxless Radeon 7730M

[g0ga@work ~]✘ xrandr --setprovideroffloadsink radeon Intel
[g0ga@work ~]✘ DRI_PRIME=1 glxinfo | grep "OpenGL renderer"
OpenGL renderer string: Gallium 0.4 on AMD CAPE VERDE (DRM 2.43.0, LLVM 3.7.0)


doesn't matter what to run, everything is going to die. kernel 4.3.3 + xorg
1.18.0, archlinux distribution, most recent at time of writing this post.
Please let me know how to provide more data for you being able to debug this. 

Thanks,
Victor