There is a new GPU benchmarking utility on the market. It is called GpuTest and the current build number is 0.2.0. It is cross-platform (Windows, Mac and Linux) and it is based on Open GL. On Windows, it runs from XP through 8.
GpuTest 0.2.0 runs only on 64-bit architecture and the developer notes that it is quite unlikely for a 32-bit variant to be released.
This is the first public version of the application and at the moment there are only three tests available, with more to come in future releases.
Only GiMark and FurMark are available for Mac systems, while, on Windows and Linux, you can deploy all of them.
Download GpuTest for Windows
Download GpuTest for Mac