Nvidia 760 4gb vs 770 2gb

I’m looking at getting a new graphics card since my current amd 7850 card is starting to die. I’m obviously looking at nvidia for CUDA support so I can use GPU rendering for cycles. The 760 4gb and the 770 2gb are both the same price and its the max I can really afford to spend any more. I’m just wondering which one of them would be better?

Hi, you can not add VRAM later and if your scene doesn´t fit it to the VRAM you can´t render.
From the core numbers the GTX 770 should be faster but it isn´t in my benchmark file, dunno why.

http://www.blenderartists.org/forum/attachment.php?attachmentid=269786&d=1384016565

Cheers, mib.