[HELP] Do I overclock?

Currently I'm using an old 'gaming' PC I got 3 year ago, current specs are a GTX 780ti, I5 processor, 8GB RAM

I'm undecided on wether to save the money to buy a brand new powerful PC (which will take a long time) or spend around £70 service to get my PC overclocked

Current state is that I can't play newish games such as PUBG, lowest settings and 40/50 fps, awful renders and common game crashing

Would overclocking my graphics card or CPU be a good option with my current PC specs, or would I be wasting my money?