Not a techie, do not play one on tv. As far as I understand, Open GL allows you to see in your display window, something much closer to what your render will be. I've only seen this in Daz studio as I'm not much of a 3D afficionado-- only dropped a foot in Bryce and spent most of my time in Poser. In Daz you can see the hair completely and the dress/outfit/whatever and the props. If the hair does fit you know it before you render. Very very nice. Same with dress etc. In Daz Studio open GL-- don't know how typical this is-- lighting was not approximated so that was dissappointing. I'd come up with dark gloomy renders that I thought were nice and bright. It may have changed, I couldn't make the change to D/S so it may. But this is what I know about Open GL as far as actual practical use-- and I had Common cards with decent recent drivers-- main probs seem to come there. Mobility Radeon on my portable and NVidia Geforce on my desktop. Emily