We managed to push the Sapphire HD7870 w/Boost to 1235mhz core and 1645mhz memory. Any higher and very minor artifacting would occur (analysed with software).
The second part of our final reveal of the Frame Rating performance methods have shown us some interesting results for the $999 and above card lineups as they stand today. The Radeon HD 7970s in CrossFire, representing the currently available and upcoming HD 7990s don't look great in our testing as we mentioned above, and I would seriously consider your buying decision before picking up this configuration.
NVIDIA's GeForce GTX 690 and GTX Titan present another debate though on the issue of single versus multi-GPU options. In our testing the GTX 690 definitely introduces more frame time variance than the GTX Titan, but the cards are so fast as it is that running the GTX 690 at single monitor resolutions like 1920x1080 and 2560x1440 don't cause a big enough problem to be a factor, thus giving it the edge because of the higher average frame rates. The GTX Titan is a powerful card and performs admirably in the single display testing but it really stands away from the GTX 690 on multi-monitor resolutions like 5760x1080 where the 6GB frame buffer can help a TON. Not having to worry about moving frames between GPUs at that resolution also helps produce a smoother animation as well. If you are buying a $1000 card and you think you might want to run NVIDIA Surround, then the GTX Titan is your better solution
Intel i5 3570K 3.4GHz CPU
MSI Z77A-G45 Socket 1155 ATX Motherboard
you will be able to do whatever you want on your machine.