One of the forced updates in W10 disabled overclocking of g3258 on chipsets not blessed by Intel.

http://forum.asrock.com/forum_posts.asp?TID=441&title=kb3064...

You have a choice of bios that lets you overclock but W10 will only work on one core, or bios that takes away overclocking and works with forced patch. At least with W7/8 you can block this particular update.