Short version: Is it possible to put another X1900 into my Mac Pro? Long version: I have a Mac Pro, bought in Oct 2006, 2x2,66 Dual-Core, 4x512 MB Ram, with a ATI X1900 XT 512MB. So far, so good! Now I need to connect 3 Beamers and one Cinema 23", that's 4 screens. Option 1) One ATI X1900 XT and one Matrox Triplehead2Go Analog Unfortunately, the Triplehead2Go Analog only supports 800x600 on the three screens when another display is connected to the other DVI port. So this option dies. Option 2) One ATI X1900 XT and one Matrox Triplehead2Go Digital Unfortunately the digital version of this card arrives in mid 2007. I need it now. Option 3) Two ATI X1900 XT So this is my actual question: is it possible to put in another X1900 easily? Apple Support (phone, Vienna) says yes. Just order the $399 ATI Radeon X1900 XT Graphics Upgrade Kit for Mac Pro. However, the BTO options of the Mac Pro don't include 2 ATIs, which is strange. Furthermore, I am concerned that the specs for the X1900 require "one x16 lane graphics slot" (according to ati.com). The Mac Pro, however, doesn't offer another x16 (according to PCI Developer Note). Will the second card run slower (max of x8 is possible when I put it into slot 2), or not at all? Will the power consumption be too much for one power supply? Option 4) Put in 2 new NVIDIA GeForce 7300 GT instead of the ATI. Reduced performance. Mixing of ATI+NVIDIA is not recommended.