my pc can't handle playing battlefield 4 mid way through game, my pc turns off and i don't understand why as i have a pulse 750w and a gigabyte gtx 970
That is a really poor quality PSU, I'd highly recommend replacing it. That could be easily be the cause of your issues.
How are your temperatures during gaming?
First, check your temps during playing games, an overheat card can make your system shut down.
Second: http://www.amazon.co.uk/Pulse-750W-120mm-PCI-EPSU-Silent/dp/B009S5JT3C
Is that your PSU?
Well, If I were you I wouldn't use that cheap PSU for sure, do not let it's number tricks you, get a better/quality PSU like Corsair, Antec, Seasonic, OCZ.