Updating Sierra to 10.12.6 ( from 10.12.5 ) solved the problem for me, and probably will for you as well.

Thanx for your reply demy076. My problem solved itself by updating from 10.12.5 to 10.12.6. After installing 10.12.6 and restarting my screen was perfect.

I still dont know why my screen was ok in  Yosemite Zone but not in Sierra Zone though.

Can I install Niresh Sierra on disk with niresh yosemite? The title says all, Can I install Niresh Sierra on my SSD with installed Niresh Yosemite without formatting and losing all? Thanks!

Post installation problems MY HARDWARE: i3 2100, Radeon HD7770 Vapor-x Overclock / GHz Edition, motherboard h61 of acer mc605 (pre-built pc). Yosemite read my GPU without problems, no ones problems. It installed MAC + boot without any kext, boot flags ecc.. and In information system says: Amd Radeon 7xxx series 1024 ecc...   Whatsup guys, I've installed correctly Yosemite Niresh version 10.10 (not 10.10.1 because 10.10 is for UEFI, and my motherboard is UEFI) and I've some problems:   -HDMI audio not working (I've tried a lot of methods, fix and many other workarounds.. but anything fix HDMI audio, Now Im using speaker through green-jack -Niresh Sierra wont update Niresh Yosemite () -on Niresh Yosemite 10.10.1 in the past I've installed 4 kexts to get control temperature of gpu, cpu etc. .working. Now on Niresh Yosemite 10.10 this method doesnt works, I've tried also to use MultiBeast installing HWMonitor, FakeMSC etc.. but nothing appaer -on my PS/2 keyboard, if I press WINDOWS KEY + @ KEY, a "@" appaer on text box, but with USB Keyboard doesnt work, I cant write "@" and other many stuffs  there is a fix to this, or a remap to use keyboard USB/PS2 as I use on Windows?   Thanks, sorry for long post, If you have only one solution, Can You help me to solve my problem? Thanks    (sorry for my bad english dudes, Im Italian!)

Kernel panic after installing mavericks 10.9 Hi, I've had a hard time installing niresh mavericks on my machine  Specs: Pentium D  3 gb ram 80 gb sata hdd 512 mb nividia gs 8400 ddr2 Every time i tried to boot the usb with some bootflags it gave me a black screen so i downloaded broyka patched kernel and replaced it with mach_kernel file in the usb . Now i could reach the installer and install the osx 10.9 even without boot flags . Now the only problem is that I cannot boot to the macintosh HD ,now its stuck on the apple logo and wont show any spinning wheel or mouse its just a n apple logo screen  I replaced mach_kernel file in hdd to broyka's patched kernel  With -v it gives me a black screen with nothing on it ( cursor or spinning wheel ) And with -v -f i get a kernel panic  Boot loader = chamelion (standard) If i boot to usb the installer works fine .