Some backstory as I understood it.
1. Asus exloited a bug allowing basic overclocking on non Z chipset
"ASUS does not guarantee that Intel new Pentium processorand Core K Series (‘Haswell’ and ‘Haswell Refresh’) processors will be overclockableon ASUS H97, H87, B85 and H81 Series motherboards in the event that Intel issues software and firmware updates that result in function changes."
2. All Motherboard manufacturers copy it
"Customers will not experience the same level of overclocking performance on non-Z sku platforms. Intel Z87 based platforms are the only platforms that support BCLK and memory overclocking, in addition to processor core multiplier overclocking. Most H87 and B85 based platforms are not designed to be overclocked and may not have sufficient margin to provide a stable overclocking experience."
"Intel plans to release a microcode update that limits processor core overclocking to Intel Z87 based platforms WW30'13."
3. Intel fixed the bug and push via Microsoft (KB3064209/Win10RTM)