Maybe I will do so.However is the first time I see a dual core card and I am interested on how they work.
Technically.
AMD = Crossfire. Nvidia = SLi
Both with some sort of 'bridge' or 'PLX' chip sitting in between the two so that both chips can communicate with each other & the system, cut down latency and handle control of pci-ex planes on the card.
Both technologies which nobody really cares about. The only people that do are extreme overclockers & benchers who want the #1 position in firestrike or similar apps. With Synthetic benchmarks, multi-GPus can pull some big numbers but when it comes to actual gameplay. Using the setup for games, the end result is often not really worth the effort.
Games are either badly optimised and not built to use such technologies and thus cause lots of problems ranging from CTDs, micro-stuttering, ghosting or weird shapes being stretched across the screen. Some developers wont even code their engines to make use of dual GPu setups. so when you start up a game, only one GPu will be used despite crossfire/sli being enabled.
Drivers on both sides can often be iffy with dual GPu support with ATi/AMD probably being the worst offender in the history between them and Nvidia. Occasionally both sides will break dual GPu profiles. but ATi/AMD will never own up to breaking anything. It took a loooooooong time and many generations of GPus for ATi/AMD to actually admit. Crossfire was completely broken and even though both cards were being used. The amount of frames being dropped by the second card meant that it was mainly one card doing all the heavily lifting.
If you want to google all this look into AMD frame pacing & runt frames. If someone didnt call AMD out for this BS. they would of carried on selling it to masses.
Putting in a second card will never give a 100% boost. The actual result is between 50-70% scaling but never 100% - youre getting less of a boost for the money you put in.
dual GPu makes more sense on lower end cards but Nvidia have gone out of their way to stop people SLi'ing low-midrange cards. Not even a GTX1060 supports SLi officially. You gotta use some software hacks to get it working.
Not to forget two cards creating more heat and eating more power as mentioned above.
But yeah --- thats how they work.
::EDT::
Also... Crossfire is dead. (They killed it off with vega) Crossfire now only works with dx12 and vulkan games. which means you wont be able to run crossfire with newer titles because your card doesnt support any of those technologies. (i think.... Though I could be wrong but thats what i get when i do a quick google)