Something about overclocking that has to be taken into account for those running Windows 10 systems from last year's free upgrade is that crashing a PC almost always results in damaged files - not just those involved in the app that crashed but all the other services going on in the background.
This means that before you start you need a reliable strategy for restoring the operating system when a crash occurs, which is where freegrade W10 systems start creating difficulties.
It is one thing to create a Windows Image Backup folder but quite another to successfully restore a system from it. The fact of the matter is that when you Restart with Shift from the Right Button Start menu to get into Repair Mode you lose control completely over whether your OS is ever going to run again.
So I would say that the first thing you need for overclocking in W10 is a DVD/USB Installation disk/stick so you can guarantee your ability to restart it.
As for the A10-7870K, it is already running in default mode just below its maximum safe voltage, so overclocking the CPU part is a case of increasing the APU Frequency while you adjust the medium settings of VRM Power Control(eg. Cpu Load Line Calibration, Cpu Current Capability, Cpu Power Phase Control, Nb Load Line Calibration, Nb Current Capability, Cpu Power Thermal Control, Cpu Voltage Frequency, Cpu Power Duty Control).
You should also bear in mind that changing Apu Frequency also changes the operating frequencies of Gpu, Memory and northbridge as well as the CPU according to the following formulae:
Cpu = Apu * CpuRatio (CpuRatio = 8.0..63.0 x 1.0) (Apu = 90..300)
Ram = Apu * Mem / 100 (Mem = 1066/1333/1600/1866/2133/2400)
Gpu = Apu * Gfx / 100 (Gfx = 445..866/917/975/1040..1950)
NB = Apu * Nb / 100 (Nb = 400..6300 x 100)
I posted a gadget that does these calculations for you. If you want to download it it's in a zip file here. If you have any difficulties unzipping it I packed it with Total Commander.