I don t know your board ,but on my 970 board i can get 4 Ghz easily.
You will need to change multiplier and the option should be available in BIOS as FX 4100 is Unlocked /BE CPU.
Go into BIOS and disable APM ,C6 and CnQ
Set the CPU MUltiplicator to the needed one for 4Ghz.Set the Turbio clock to Disable or to the same 4Ghz.
Restart.
Check for stability with CPU stress tests then try and lower the voltage a little ,it should hover to around 1,28V in BIOS monitor.
Using less voltage will mean less heat.Stock cooler is enough if you have a good airflow in the case.
Enjoy.
Don t expect huge performance increase though in games.
If you want to not use the Multiplier for some reason you need to increase the HTT(FSB) clock from 200 up.
You will also need to readjust the HT Link with a lower HT Multiplier and change the RAM devider to lower one so you keep the memory in specs.
CPU clock =HTT(FSB) X CPU Multi
HT Link=HTT X HT Multiplier
HT Link should be under 2400Mhz all the time
RAM should be set so you don t go over the rated speed.
I almost forgot.If your board is not meant for over-clocking you may brick it after this session.