Well let's start with this:
Keep checking this link for official updates, it is more likely they will put updates here first, before EU support pages.
http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/modelContent.jsp?modelFilter=X770-ST4N04&rpn=PSBY5U&category=&selCategory=2756709&moid=3039260&os=&ct=DL&selFamily=804517
OK, now I will just describe what I did. Later I will mention what has changed.
Download new BETA drivers from Nvidia or that laptopvideo2go site.
I did not use their modified INI file. Just start installation and when asked choose CUSTOM setup.
Now you may choose which components to update I chose all and I didn't do "clean" install, I left that last option checked.
Next thing is download EVGA Precision or MSI Afterburner. These programs are for clocking GPU cards.
You will have to underclock your GPU if you have freezing and lagging in games.
I undeclocked core clock to 675 as Juju said in some post. Don't forget to click APPY when changing setting in program.
I have to say I also use cooling pad CoolerMaster Storm SF-19 and I turn it all the way up when playing a game. And I did BIOS update. Also I mainly use external monitor.
Things that are changed.
Eco mode button does not work. You can still change power consumption settings through control panel.
3D mode if it is enabled it is always turned on when game is started. You can turn it off by pressing 3D button on your notebook.
Occasional blue screen occurs.
I might forgot to mention something but I will edit if I remember later or discover another glitch.