One of our concerns at Folding@home is the reliability of returned results - when you run on hundreds of thousands of machines around the world, in diverse environments, it's virtually guaranteed that some machines will be faulty. We've long advocated the use of reliability-verification tools to make sure your machine is working properly, especially for users who overclock their machines. While good utilities are available for this task on CPUs and system RAM (e.g., StressCPU and Memtest86), few tools are available for these tasks on GPUs because of their relative novelty.
Last year, we released the MemtestG80 GPU memory checker, an analog to Memtest86 for NVIDIA CUDA-enabled GPUs. This has been widely used by the community to catch misbehaving video cards. To bring this testing capability to a wider audience, we've just released a new, OpenCL-based GPU memory tester named MemtestCL. Because it's based on OpenCL, users of ATI video cards (Radeon 4000 series and newer) are now able to validate their GPU memory as well as users of Nvidia video cards. Both MemtestG80 (CUDA) and MemtestCL (OpenCL) implement the test patterns from Memtest86 (as well as a couple custom patterns) to make sure your GPU memory is working correctly.
If you run FAH heavily on a GPU, especially if your card is overclocked, it's a good idea to check your GPU memory, in the same way that you'd run Memtest on CPU memory. Both programs are available from the FAH utilities download page (http://folding.stanford.edu/English/DownloadUtils); people interested in looking at the source code can find LGPL-licensed copies on the project's SimTK homepage: https://simtk.org/home/memtest.
