We've just released MemtestCL, a dedicated memory tester for OpenCL-capable GPUs in the same vein as MemtestG80 for CUDA-capable GPUs. In particular, this means that owners of ATI OpenCL-capable GPUs (the Radeon 4000 and up) can test their GPU memory as well. Binaries for Windows and 64-bit Linux are available, as is (LGPL-licensed) source code for those of you interested in doing additional development work (for example, GUI frontends).
Note that you must have an OpenCL-capable driver and runtime installed on your machine for this to work. For Nvidia, this means a 195 driver or newer; for ATI, you need the Cat 9.12 or newer video drivers, AS WELL AS installing the ATI Stream SDK (
http://developer.amd.com/gpu/atistreamsdk/) - for some reason the OpenCL runtime does not come with the video driver. Incidentally, by installing the Stream SDK, you can use MemtestCL to test your CPU memory too.
Source and binaries are available at
https://simtk.org/home/memtest. Binaries may also be found (without the SimTK mandatory registration) on the official FAH utilities page:
http://folding.stanford.edu/English/DownloadUtils
