Right then, here we have the 9" long Radeon HD 6790. First impression, the reference cooler hints a lot to the R6870 series alright, with the exception of minor tweaks of course. The cooler used on the R6790 is more than sufficient and even under hefty stress will rotate at 30 to 40% of it's fan RPM capacity. The PCB is absolutely different compared to the 6850 series though.
Our reference card comes with two DisplayPort 1.2 connectors, one HDMI 1.4a connector and two DVI connectors of which one is single and the other dual-link. If you have a very high resolution monitor at 2560x1600 you'll have to use the dual link DVI connector.
Now hold on, above the backside of the R6790 ... and now let's look at another photo:
Can you see the resemblance ? Above is the the R6870 PCB, which is the very same components and placement. We are not 100% sure just yet but we think that if you flash a R6870 BIOS into the R6790 ... you might end up with a perfectly fine working R6870. This is just an observation of course, not at all a guarantee.
At the top side (as the board is a little longer) we spot two 6-pin PCIe PEG headers, the board has a rated TDP of 150W, again similar to a R6870. Each 6-pin PCIe PEG connector can carry 75 Watt and the PCie bus another 75W. These are of course theoretical figures, a PSU can push through much more.