Aside from the usual PC GPU performance leapfrogging game, the professional OpenGL workstation market, focused on engineering, science, simulation and media content creation, is still strongly dominated by nVidia Quadro cards, with their combination of performance, large memory capacity for both OpenGL and CUDA GPGPU jobs, with a very wide optimized certified application support and excellent Linux drivers, something where ATI still has some work to do.So, getting a high end nVidia Quadro OpenGL card is a special experience, no doubt. Getting two of them - especially when it is a pair of those lovely 4 GB FX5800 cards, the current cream of the crop before the 6GB FX5900 comes out - is one of a kind experience. Then, NOT being able to run them in SLI for months because the Quadro Detonator drivers automatically disable the option if you're not running the cards on one of the select few 'branded' workstation, is a major disappointment. Yes, you've read that correctly. Unless you purchase a nVidia certified workstation, drivers will automatically disable SLI mode EVEN if you are a system vendor that appears on nVidia Workstation System Builders list. We have received numerous explanations from nVidia's otherwise excellent Quadro PR and Engineering teams. However, various explanations given to us such as "Quadro SLI is disabled if a driver detects hardware ID 3405 [X58 chipset] and enables it [Quadro SLI] if a driver detects hardware ID 3406 [5500 Series Chipset]" are simply not true.