Intel has made a move to stop the overclocking of its standard (i.e. not unlocked 'K' model) Skylake processors.
News that such overclocking was possible first emerged last December, when Asrock revealed a new BIOS update that permitted it on the firm's Z170 motherboards. This meant users could take a cheap Core i3 Skylake CPU and crank it right up with a big overclock (just like back in the good old days).
However, at the time it was thought likely that Intel would block this BIOS workaround, and indeed this has now happened.
Intel told PC World that it's priming a microcode update to put an end to this practice. The company also noted that performing such overclocking isn't a good idea, and indeed if you engage in juicing up your CPU like so, it will void your warranty as the processor is being pushed beyond its design spec.
An Intel spokesman said: "Intel regularly issues updates for our processors which our partners voluntarily incorporate into their BIOS. The latest update provided to partners includes, among other things, code that aligns with the position that we do not recommend overclocking processors that have not been designed to do so. Additionally, Intel does not warranty the operation of the processor beyond its specifications."
In other words, if you want to overclock, Intel is insisting that you should pay the premium for a 'K' unlocked CPU, which has been the case since Sandy Bridge was first introduced.
Of course, if you've already overclocked your Skylake processor in this way, you could always choose not to update to the new firmware that tackles this issue, whenever it's rolled out.