Hi Jeff, I don't know much about any of the current Apple graphics cards (Radeon HD 2600 XT 256Mb, Nvidia GeForce 8800 GT 512Mb, Nvidia Quadro FX 5600 1.5Gb). My first concern would be whether bugs in the drivers for these cards are going to cause trouble in Chimera. We have a web page that lists problems with graphics drivers observed using Chimera: http://www.cgl.ucsf.edu/chimera/graphics/graphicsbugs.html#cards There was a recently reported problem (squashed atom spheres) with GeForce 8800 GTX (not GT) on Windows. The Apple driver may be much different. The Quadro FX 4500 which was Apple's high-end offering before the 5600 crashed with solid volume rendering. Don't know if the current 5600 would have the same problem -- but there is a fair chance it does. Chimera uses many different OpenGL calls and I'd guess 1 in 10 drivers exhibit bugs of varying severity when using Chimera. Some of Chimera performance is related to graphics card speed and memory, and some is related to CPU speed and memory. When the displayed models rotate slowly that is the graphics card except if you are using transparent volume surfaces or meshes which are sorted by depth on the CPU for every new view angle. Everything else is the CPU, main memory, memory cache performance, and hard-drive speed. Solid style volume rendering makes a lot of textures which usually will be stored in graphics card memory. More graphics card memory could make larger volume rotate faster because they fit on the card. 256^3 volumes (16 million voxels, 4 bytes per voxel) typically rotate at 10 frames per second with graphics memory sizes 128 Mb and up. Textures have to have power of 2 sizes so just knowing that can get you better performance if you trim your 550x550x100 region to 512x512x100 you'll get a factor of 4 speed-up. I don't know if a single application using one display can use more than one graphics card in Apple's multicard options. Chimera has no special code to do that. For large volume data, hard-drive speed, main memory size, and CPU speed are likely to be noticable factors in Chimera performance, each of about equal importance to graphics card speed. Tom

hi Tom,

if you were considering a Mac Pro at some point in the future, what graphics card would you pick when thinking of chimera (if you don't mind peeking at some point at the list at http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/9354001/wo/G...

are rendering bottlenecks in chimera largely a processor-limited thing (and thus one of the 'lower end' cards listed would be fine), or something that benefits dramatically from spending $2000 on a graphics card (I am not in that kind of market, just wondering what kind of decision you would make if evaluating that platform)

best,

-Jeff