1. You should follow this hardware and setting guide located here:
https://github.com/litecoin-project/litecoin/wiki/Mining-hardware-comparison , give that a shot with some predefined settings and see how that goes - a lot of people have luck using that.
2. You do not need to install the SDK, all the recent drivers have it included. If you install both, they could be overwriting eachother which is something you don't want.
3. With 12 in mind, the most common issue with this card (I have a bunch of) is the thread concurrency, and correct clocks. It is totally necessary to play with the clocks for this to get the speed that will help you out, because they can be finicky. Every system is different. Make sure when you finally find a good clock that you have 0 HW errors, as it can damage the card if you start to get any.
4. Consider flashing the bios, it will reduce the power consumption and save you 50watts on each card, you are looking for the newest F43 bios.
Good luck