January 11, 2013, 05:06:05 pm
Sorry to be slow to reply to this thread. I had the 3GB GTX 580 and it's great, but I recently spec'd out two new Lumion PCs with 4GB GTX 680 and it made a huge difference - faster render times and faster build-mode frame-rates. I'm afraid I didn't bother with making a test to find out exactly how much better the 680 is, but my impresssion is about a 2x speed boost.
Another reason for switching to the 680 is that the 680 has a Displayport output. Displayport supports billions of colors (for wide-gamut monitors) while the old DVI output only supports a max of 16.7 million colors. Not particularly relevant to Lumion, but I like the additional color support for my Photoshop work. And, of course, it's great having more video memory for big Lumion projects!
Oh, and one last really nice thing about the 680...uses about 100 watts less power (check the specs to be sure).