Dont bother with overclocking, yes there is unlocked bios for x230 but theres no point risking bricking your laptop.
cpu is soldered on the motherboard, you could either replace motherboard with i7 cpu
Or buy faster ram, replace with 2133mhz ram kit, chipset should support up to 2400mhz but that is very expensive ram, would not recommend it. (check and search compatibility first for certain ram)
And you can always make egpu setup, x230 works well with expresscard exp gdc :
View: https://www.youtube.com/watch?v=p59MNoqWY9c
Use only nvidia cards since AMD wont work in internal monitor.
For egpu you need EXP GDC beast, cheap used psu, cheap gpu (nvidia)