When I connect a display via a Dual-Link adapter (tested original Apple and Dr. Bott) to the external Mini-Displayport of my Macbook Pro 17" 2009 I don't get full 8 bit per channel color depth (or at least it's seriously messed up with heavy banding), neither in native resolution (2560x1600) nor in non-native (1920x1200). Running the same display via the same cable over a passive Single-Link adapter works perfectly well (all 256 shades of grey present). I tried two different cables (both a Dual-Link and a Single-Link cable, both of which work with the Single-Link adapter). So either both Adapters are bugged the very same, or the 9600M GT does something wrong when a Dual-Link adapter is connected. It could also be a driver issue, but at least the internal display doesn't show any banding when running in Clone mode. Same happens on OS X with both the 9600M and 9400M. So either both adapters ain't working properly or there's something wrong with the combination of NVidia 9x00M and Dual-Link DVI. And I tested three more single-link displays (1x 1920x1200, 2x 1680x1050) and only one works (the 1920x1200 Viewsonic VP2330), the other two show the same problem with both Mini-Displayport to Dual-Link DVI adapters. Then I tested connecting a current ATI based IMac 21.5" to one of the not working displays (a Samsung) and there worked with both adapters. So it seems that the 9400/9600M in the Macbook Pro output a signal of lower strength (compared to the ATI based Imac), which leads to signal degradation once coupled with a Dual-Link adapter. The reason why the VP2330 works probably is because it can work with weaker signals. That doesn't help me at all with my 30" display though and only 1 working display out of 4 is rather disappointing.