Passive cooling is the problem. Any video card these days has to be capable of running the 3D in Vista/Windows 7 and Mac OS X. That means heat which necessitates a fan. There are passively cooled cards but they're either high end stuff with fancy physics involved in heat transfer or very low end stuff but then that's all you need.
Additionally all cards are capable of running at x16 PCIe though any will run on x8.
More programs are using the graphical capabilities of the cards to boost 2D work.
I found this one which might do the job:
http://www.amazon.co.uk/NVIDIA-Quadro-2 ... 402&sr=1-1
Bear in mind it's more than possible to buy a card with a fan and swap the fan for a third-party heat sink or other passive system.