The cheapest video card for rendering Premiere Pro

Hi guys! Help! I'm not experienced user. I need a very cheap discrete video card for my computer which take part in video rendering (accelerating) in order to render videos faster. As far as I understand - I need nvidia, but will for example very cheap gt 710 2 gb, gddr5, take part in finishing video rendering to do it faster and if yes then how faster that finish rendering (%) than without it? I need it for a few weeks replacing it with another videocard, so I don't want to spend much. Thank you!