I have tried with Mageia-6-rc-x86_64-DVD and the live plasma DVD, both downloaded with qbittorrent, both md5sum verified, both burned to an ADATA 8GB usb key with IsoDumper, which verifies the burn, in MGA 5 (two separate burns, same key).
The hardware is Mobo: ASUSTeK model: Z170I PRO GAMING using the onboard graphics of i5-6500 CPU. I'm currently running ROSA Desktop Fresh R8.1 release 2014.1 for x86_64 on this machine for a half-year or so with adequate functionality. There were challenges getting distros to work with Skylake last year, but the kernel has matured and, for example, i915.preliminary_hw_support=1 as kernel command should not be needed. I tried adding it to the kernel options, anyway, but no difference: the screen goes to black after kernel loads, the monitor light stays on, showing there is a signal, but no more.
I boot the Z170I with usb key inserted, press F8, and get options to boot from ADATA or eufi ADATA. I don't know what eufi does for me except complicate things, so I avoid that as a first choice. After no installation or live session being presented to me, I tried the eufi option. Interestingly, the boot menu gives me boot from DVD and boot from USB options. I choose USB and a black screen appears in the middle of the boot menu screen and stays like that. Boot from DVD acts the same.
This is an HTPC, not the primary machine. The primary monitor is an old Viewsonic at 1024x768 connected from onboard connector by HDMI to DVI adapter. The display monitor is an LG LED widescreen connected from onboard display port to HDMI adapter. As I said, I've got this working with ROSA and other distros from last year.
Finally, I disconnected the HDMI cable to the LG widescreen and tried several more times with the classical installer iso on usb key. Magic keys still work if I don't wait too long (5 minutes) for something to happen, it seems. After long waits, I have to use the power button.