I took the XFX plunge

Hey guys and gals just purchased a XFX r9 290x DD and I gotta say...wow!! A lot better than what I had before. I was running two MSI GTX760 Twin Frozer in sli. It just seems to me that the r9 runs things a lot smoother. I also like the way the card looks...one the best looking cards out now imho. If you guys have any pointers on how to get better performance out of this card...I would gladly appreciate it.

Use msi afterburner and overclock it.

Msi Afterburner or ASUS GPU Tweak (i use GPU Tweak with Asus bios flashes).

Don't turn on AMD's Overdrive application.

Afterburner has more options but GPU Tweak seems to run the power % better for some reason , I found Afterburner would reset to 0% power sometimes.

Your seeing a few things happening with your perceived performance gains.
1. SLI vs single card performance stability , SLI is great when its scaling 100%.
2. Memory increase in usable Video memory can help alot in some games.
3. I personally have always found even from back to ATI days my ATI/AMD cards appear to me Cleaner/Crisper image wise and that could be to do with the LOD trickery Nvidia likes to do. and less image hitching on average which has plagued me on at least 3 Nvidia cards of dif generations.

Perhaps not every Nvidia Generation suffers from these disparities/issues but I've went back and forth quite evenly through out the last 15 or so years and its just been one of my observations esp on image quality/clarity.

I should Add GL with your card , I hope it works good for you and doesn't develop any of the issues some of the other 290's have seen. If you have a good one then it will be really good to you!