ffmpeg undervolting
$ sudo intel-undervolt read 
CPU (0): -75.20 mV
GPU (1): -0.00 mV
CPU Cache (2): -0.00 mV
System Agent (3): -0.00 mV
Analog I/O (4): -0.00 mV



baseline: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080

cpu-85-cache-0: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080

cpu-85-cache-50: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080

cpu-85-cache-75: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080

cpu-85-gpu-25: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080

cpu-90-cache-0: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080

cpu-75-cache-0: 

	Processor: Intel Core i5-4210U @ 2.70GHz (4 Cores), Motherboard: LENOVO Cherry 4A, Chipset: Intel Haswell-ULT DRAM, Memory: 8192MB, Disk: 256GB Samsung SSD 850, Graphics: NVIDIA GeForce GT 730M 2048MB (719/900MHz), Audio: Intel Haswell-ULT HD Audio, Network: Realtek RTL8111/8168/8411 + Intel Wireless 7260

	OS: LinuxMint 18, Kernel: 4.4.0-142-generic (x86_64), Display Driver: NVIDIA 384.130, OpenGL: 4.5.0, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080


FFmpeg 3.4.1
H.264 HD To NTSC DV
Seconds < Lower Is Better
baseline ........ 29.54 |======================================================
cpu-85-cache-0 .. 17.25 |================================
cpu-85-cache-50 . 17.48 |================================
cpu-85-cache-75 . 17.45 |================================
cpu-85-gpu-25 ... 17.29 |================================
cpu-90-cache-0 .. 17.34 |================================
cpu-75-cache-0 .. 17.36 |================================