Low Profile PC's with High-End Video Cards?

tsetem asks: "We have an application where we have to deliver 7 PC's running Linux, all capable of doing higher-end OpenGL Accelerated graphics, being rack mountable, and being able to fit into a trailer. My plan was to get either a 1U or 2U system, or a complete PCB with a decent graphics card on it. I've been looking all over the Web, and on various websites to see if there are any Slimline PCs that are capable of running high-end Video Cards (like Matrox, 3dfx, or NVidia). All of the systems I've seen are the Intel, C&T, or some other chip which is fine & dandy for 2D, but 3D acceleration isn't there. Has anyone run across a 1U or 2U system, with a high-end video chip built into it, or with an AGP slot so I can use my own?"