Hi Ryan, Take a look at the Chimera graphics benchmarks page to get an idea how various graphics cards perform. http://plato.cgl.ucsf.edu/trac/chimera/wiki/benchmarks If you are using surface rendering in volume viewer then the relevant number in the benchmarks is the surface score. It indicates the size N of a cube that can be rendered at 10 frames per second where each face of the cube is rendered as 2*N*N triangles. For your map (from the size I guess a virus) you are probably getting slower frame rates than for the benchmark cube at 550^3 size because the virus contour surface has onion-like internal layers. Even though those layers aren't visible they take lots of time in the rendering. You could clip the map (use Favorites / Side View and move left yellow vertical line to the right) to see the internal structure. If there are many layers at the contour level you like and your primary interest is the protein layer of the capsid you might consider making a new map where you zero the interior (genome part) of the virus. You can perhaps use Chimera volume eraser or the "shape sphere" command and "mask" command. This will make the surface have many fewer triangles giving faster rendering. I think your graphics rendering rate is not being limited by graphics memory, but rather by GPU speed. A look at the benchmark web page at cards with different amounts of memory will give you an idea of what you can expect with more memory. The benchmark test cube has 12*N*N triangles so a benchmark surface score of 1000 means 12 million triangles are rendered 10 times per second -- ie. 120 million triangles per second. You can see how many triangles per second you are getting with your map. Select the map surfaces (ctrl-click) and use Actions / Inspect. The number of triangles will be listed at the bottom. Then Tools / Utilities / Benchmark will allow you to measure the frame rate. Clear the selection before measuring the frame rate because the selection outline is rendered with a 5-pass drawing algorithm that greatly slows the rendering. Use the "Measure frame rate continuously" checkbutton. Tom -------- Original Message -------- Subject: [Chimera-users] Maximizing performance with large volume data maps From: Ryan Rochat To: chimera-users Date: 12/4/09 7:15 AM

Hello, I was wondering how much video memory Chimera is capable of accessing. I currently have a 898Mb videocard that begins to slow down with a 550x550x550 map (at step size 1). This map is actually a downsample of the true 1100x1100x1100 map coming in at 5GB. I was contemplating going for a much larger video card at 4GB, however I was curious to what extent I could expect to see acceleration using Chimera with such a massive dataset (600+MB) and video card.

Thank you, Ryan H. Rochat MS MD/PhD Candidate (Baylor College of Medicine) Graduate Student SCBMB (Baylor College of Medicine) Chiu Lab One Baylor Plaza N420 Alkek Houston Texas 77030