Since there isn't a lot of BOINC related threads and how to discussions, I figured I would add one. To run more then one GPU at a time in BOINC: 1. You need to create an .xml file using Notepad or other text editer. 2. Name the new file cc_config.xml 3. In the file you need to add: <cc_config> <options> <use_all_gpus>1</use_all_gpus> </options> </cc_config> 4. Save this file to your BOINC data directory. In Vista/7 it is in a hidden folder named C:\Program Data\BOINC\ In Windows XP is is normally in C:\Documents and Settings\All Users\Application Data\BOINC\ 5. Restart the BOINC client so that it reads the file if it was already running. To run GPU work in BOINC 1. Make sure BOINC is NOT installed to run as a service. BOINC can't run GPU if it is. 2. Make sure you have up do date drivers installed. - In the case of Nvidia GPUs, you'll need an up-to-date driver. - In the case of ATI/AMD GPUs, you'll need an up-to-date APP driver. In the case that your GPU cannot support the APP driver, for whatever reason, you'll need to install the ATI Stream SDK for Windows and Linux, since it contains specific libraries that are needed. You will also require Catalysts 10.4 or above. The SDK page will tell you which Catalysts are required for the latest SDK. So far: - SDK v2.1 needed 10.4 - SDK v2.2 needed 10.7 - SDK v2.3 needed 10.9 - SDK v2.4 needed 11.3/11/4 - SDK v2.5 needed 11.7 You will need to install this SDK as AMD does not allow that projects distribute the needed libraries on their own yet. Macintosh OS X 10.6 has these libraries built in.