All three of them stick to the design and specs, changing only the boxNVIDIA launched the GeForce GTX Titan super-powered graphics adapter just days ago, and while the company does intend to sell only a limited number of them, it does not mean to prevent its partners from shipping some.
That said, it would appear that all of the company's partners have one card to ship.
ASUS, Zotac and EVGA are three of them, and they did not modify the design or performance in any way.
Indeed, the video cards look the same, though the boxes have different looks of course. EVGA is the only one that we've seen, so far, with a second model, one using water cooling.
All of them have 6 GB of GDDR5 VRAM, GPU clock speeds of 837 / 876 MHz (base, GPU Boost 2.0), a 384-bit memory interface and two dual-link DVI ports, one HDMI and one DisplayPort. Prices are to be announced.