"The card has two DVI ports, two mini- DisplayPort and one HDMI port. AMD's display output logic is clearly superior to what NVIDIA has to offer at this time. Vendors are free to combine six TMDS links into any output configuration they want (dual-link DVI consuming two links) - and use them all at the same time. AMD has also introduced DisplayPort 1.2 support with their new cards which allows the use of a DisplayPort hub to connect multiple monitors, or daisy chain them together. "
http://www.techpowerup.com/reviews/HIS/Radeon_HD_6870/4.html
(same words for 6850 just one display port not two mini-display port
iirc 5*** series had 4 clock sources ,now you are telling 68** series has 4 clock sources not 6 ,correct?
Not sure what you mean there, but fundamentally, in terms of the display clock sources HD 6000 is the same as HD 5000; there are two sources for legacy devices and one source for DP (which can be shared accross multiple DP outputs).