Since you are suggesting you might go for a 1440p monitor go for a HD 7900 series card . The extra bandwidth proves its worth in demanding games like Metro 2033, Crysis Warhead.
You wouldn't want to run into any bottlenecks after spending close to 500 dollars.
XFX Radeon HD 7950 DD Black edition review
http://www.hardocp.com/article/2012/03/01/xfx_radeon_hd_7950_black_edition_video_card_review/7
XFX Radeon HD 7950 DD Black edition (900 Mhz) - $449
http://www.centrecom.com.au/catalog/795a-tdbc-radeon-7950-double-dissipation-black-edition-p-56300.html?sort=3d
Sapphire HD 7950 OC Dual X - $ 459
http://www.centrecom.com.au/catalog/1196-sapphire-radeon-7950-overclock-p-56304.html?sort=3d
Sapphire's Dual X is the best cooling solution. You can keep the card cool at very high overclocks. Getting the HD 7950 OC to 1050 Mhz in AMD CCC is straightforward. For 1080p performance that should be more than enough. When you need the extra performance open up MSI Afterburner (non sapphire HD 7950 card) or Sapphire Trixx (sapphire HD 7950) and get this card to 1150+ Mhz.
A couple of examples to show what happens when GTX 600 cards are bandwidth constrained
Metro 2033
http://www.guru3d.com/article/radeon-hd-7950-overclock-guide/
http://www.guru3d.com/article/asus-geforce-gtx-670-directcu-ii-top-review/16
http://www.guru3d.com/article/asus-geforce-gtx-680-asus-directcu-ii-top-review/18
Very high with DOF (AAA) 1080P
HD 7950 (1150 Mhz ) - 50
GTX 670 (1058 / 1137 ) - 39
GTX 680 (1137 core / 1267 Boost) - 41
Crysis Warhead
http://www.anandtech.com/show/5476/amd-radeon-7950-review/6
http://www.anandtech.com/show/5699/nvidia-geforce-gtx-680-review/7
2560 x 1600 Enthusiast 4x AA
XFX HD 7950 (900 Mhz ) - 34.4
HD 7950 (800 Mhz) - 31.1
GTX 680 - 30.8
From the GTX 680 review
"While Crysis was a strong game for the GTX 580, the same cannot be said of the GTX 680. NVIDIA is off to a very poor start here, with the Radeon HD 7970 easily outperforming the GTX 680, and even the 7950 is tied or nearly tied with the GTX 680 depending on the resolution. On the bright side the GTX 680 does manage to outperform the GTX 580, but only by a relatively meager 17%.
Given the large gap in theoretical performance between the GTX 680 and GTX 580, as it turns out we’ve run into one of the few scenarios where the GTX 680 doesn’t improve on the GTX 580: memory bandwidth. In our overclocking results we discovered that a core overclock had almost no impact on Crysis, whereas a memory overclock improved performance by 8%, almost exactly as much as the memory overclock itself. "
There are other demanding games like Alan Wake, Witcher 2, Shogun 2, Anno 2070 where a HD 7950 OC will easily beat a GTX 670 OC.
http://www.hardware.fr/articles/866-9/benchmark-alan-wake.html
I don't know about you but I would consider the performance lead in games like Metro 2033, Crysis Warhead more important because it gives and idea of how the cards perform when al the resources are stressed out - shading power, ROP, bandwidth. In games like Skyrim, Dirt 3 where GTX 670 leads both the cards are comfortably doing 70+ fps at 1600p. Also HD 7950 OC scales perfectly with extra clock. So at 1100+ speeds the gap would be negligible in such less demanding games
Edited by raghu78 - 5/20/12 at 10:03pm 
