The Haswell platform was where Intel introduced FIVR or the fully integrated voltage regulator unit. This placed some of the VR (Voltage Regulation) on the die allowing for motherboards to have less power phases on board. For the upcoming Skylake and including next years Kaby Lake, Intel has decided to go back to the traditional power delivery system with voltage regulation done solely on the motherboard. The main purpose of voltage regulation is to supply voltage to the CPU and maintain or stabilize the demands of the processors.
With FIVR, it served one task, to control Vcore, Vgpu, VCSSA, VCCIO and PLL. The FIVR block on the die also added to heat output which was featured on an already dense 22nm processor. While the latest reports have said Intel will do away with FIVR placing voltage regulation back on the 100-series motherboards, It is rumored the in 2017, Intel will re-introduce FIVR on the series following Skylake and Kaby Lake although the platform’s codename is not confirmed.