The best graphics card for my mobo?

Im currently using ASUS M5A99X EVO. what would be the best gpu for my mobo ? regardless of the price.

Well lets see what the best regardless of price has to offer.

• EVGA SuperClocked 02G-P4-2682-KR GeForce GTX 680 2GB 256-bit GDDR5 PCI Express 3.0 x16 HDCP Ready SLI Support Video Card
• GIGABYTE GV-R797TO-3GD Radeon HD 7970 GHz Edition 3GB 384-bit GDDR5 PCI Express 3.0 x16 HDCP Ready CrossFireX Support Video Card

or if you prefer Dual GPU in one package.

• EVGA Signature 04G-P4-2692-KR GeForce GTX 690 4GB 512-bit GDDR5 PCI Express 3.0 x16 HDCP Ready SLI Support Video Card

what about this AMD beast that just launched a few days ago. Newegg doesn't have it in stock so you would have to look elsewhere for it.

• PowerColor Unleashes the Devil: World's First Dual-GPU Radeon HD 7990 Graphics Card Launched.

If you really did mean "regardless of price" then yeah the GTX 690 or upcoming HD 7990 are the fastest single slot solutions, but they are absolute overkill for resolutions of 1080p and under.

My mobo's pcie is only 2.0 . can a 3.0 pcie card will run along with my mobo ? note : my crossfire build will run on x8 for dual gpu/ dual card ( in my understanding ). x16 is for single card / gpu .

PCIe 1.0, 2.0, and 3.0 are forward and backward compatible.

• If the card and motherboard supports PCIe 3.0, that will be the standard used.
• If the card and motherboard does not support 3.0, the standard will fall back to the newest standard supported by both.

If I remember correctly AGP x4/x8 was a multiplier for the cards speed capabilities. With PCIe x16 is the number or lanes (16 parallel independent serial data connections) at which data is transfered. And if I'm not mistaken the PCIe 2.0 and now PCIe 3.0 were frequency jumps, effectively doubling the speed at which PCIe operates.

PCI-E 3.0 offers double the bandwidth of 2.0 so PCI-E 3.0 x8 = PCI-E 2.0 x16.

PCI-E 2.0 x8 might be a slight bottleneck for the highest end cards (7970, GTX 680), but there is no almost difference between PCI-E 2.0 x16 and PCI-E 3.0 x16 for single GPU cards.

Would this equation mostly be used when SLI or Crossfire is implemented therefor dropping a x16 slot down to a x8 slot? If the motherboard was capable of supporting both cards at x16, would you even need to think about x8 bandwidths?

ASUS M5A99X EVO

Expansion Slots
2 x PCIe 2.0 x16 (x16 or dual x8)
1 x PCIe 2.0 x16 (x4 mode, black)
2 x PCIe 2.0 x1
1 x PCI

Impression I got from OP was that he was thinking of running a CF or SLI setup.