This card is a good start and is DX11 with openGL 4.0. http://www.newegg.com/Product/Product.aspx?Item=N82E16814133324
Single slot and has 3 display connectors.
This card is on par with the Quadro FX 5800 spec wise and uses much less power. Better really since it has GDDR5 with is double the bandwidth of GDDR3 and there is 2GB worth of vram so this card will pay for it's self. 256 shaders are better than 240 and is based on the G104 gpu.