If it was OpenCL, I would expect the nVidia to do a lot better. G
It works fine with older cards. I have a couple HD 3870's running it and they work OK: http://moowrap.net/results.php?hostid=608 and http://moowrap.net/results.php?hostid=7307 So does my HD 4830: http://moowrap.net/results.php?hostid=3686 Even my single precision HD 5450 works: http://moowrap.net/results.php?hosti...&state=3&appid=
So, either they upgraded the app to support older cards, or maybe it was DNETC that didn't support the older cards. I don't recall.