gtx750 is more powerful than a r7 250.
they both have low power requirements and may run with your local PSU, but it is recomended u buy a better (certified)psu.
You should first buy a decent PSU as this Intex PSU may not handle the GPUs.
If you will install the card with this PSU then you are risking your computer's components........for safety, you must buy a decent certified PSU with over 80% efficiency and with enough AMPs on +12V Rail.