Only a few weeks ago AMD launched the fastest video card to date, the RADEON HD 6990. This uses two of its graphics chips to deliver the kind of framerates needed to game on the Eyefinity multi-monitor setups that the company supports. Now it is NVIDIA's turn to enter the dual GPU market, with the GeForce GTX 590.
This beastly card comes with 3GB in total memory, which connect to two of its top of the range GPUs. They run a little slower, but combine using NVIDIA's SLI technology to deliver a performance boost somewhere in the range of 1.5x the performance. It draws 365W of power, and it is reccomended that you have at least a 700W power supply in your PC. It can also put out a lot of heat, which requires deft usage of case fans. Lastly, it is 28cm long, so you'll need to measure if theres enough space to actually mount it in a PCI-Express x16 slot.
NVIDIA has been focusing on its 3D Vision technology for some time now, with its LCD Shutter glasses the most commonly used 3D solution for PC gaming. This means that it has come a little late to the multimonitor party, and this is actually the first NVIDIA card capable of running three monitors.
The reason behind the difference in monitor support is largely down to silicon design. AMD has gotten behind the highly flexible DisplayPort standard, and uses that to support large numbers of screens. NVIDIA has stuck with DVI, each port of which requires a dedicated controller.
From our testing the GTX 590 is a pretty impressive card, but the sticking point is that the cards listed on websites to date are over $1000. The competing RADEON HD 6990, which is quicker, retails for a few hundred less than that. We would probably wait until prices settle a little before grabbing one of these monsters.