A single 7950 GX2 packs the wallop of two single-GPU cards, falling in somewhere between the level of two 7900 GTs and two 7900 GTXs. The first and foremost point to make when talking about the GX2 is that is brings SLI performance to just about anybody - as long as your board supports it. Obviously, placing two of these GPUs so close together is bound to build up some heat. To downplay this issue, the 7950 GX2 has been clocked down to 500MHz, which also should mean some lower voltages, and thus lower temperatures.
Each GPU is installed on its own PCB with separate cooling solutions and memory. For the most part, the power circuitry has been moved towards the bracket end of the card reducing its size to a tidy nine inches. Differing from the older 7900 GX2 setup, only a single "goldfinger" connection is needed to connect more two cards for SLI, and only one 6-pin power lead is necessary per card. For a full technical briefing on the 7950 GX2, feel free to check out our 7950 GX2 launch article.
Installing two 7950 GX2s really doesn't involve anything advanced as far as the procedure goes, but there are some caveats. For example, installation on the GA-8N-SLI basically took up all of the available slots from PEG 2 downwards, and caused some wiring issues with the SATA cables for the hard drives, as they are placed right at the end of the video cards. Obviously, one needs to consider all facets before walking down this road.