I am also having this issue. I have Speedstep disabled, Windows power plan on high performance, and tried setting cpu multiplyer at 45 with turbo off. Still the cpu will throttle down to 1.6 at idle. CPUZ shows this with base clock at 100 multiplyier 16-45. I can't find a way to make it just stay at 45 all the time. My CPU is i7 3770K with ASUS Maximus V Formula.
Case: Custom built desk mod. * CPU: Intel Haswell Core i7-4790K * Motherboard: ASUS Maximus VII Formula Z97 * Memory: 16 GB of DDR3 from GSkill * Hard Drive: RAID 0 array using 2x 250 GB Samsung Evo SSDs for the operating system. * GPU: EVGA Nvidia GeForce 670 (x2) in SLI * Power Supply: OCZ Fatality 1 Series 1000 Watt PSU * Optical Drive: LG BluRay Burner * Operating System: Windows 8.1 Pro * Monitors: ASUS 23" 120Hz 3D Monitor (x3) * Cooling System: Custom water cooling loop.