Unigine Heaven 4.0
“Heaven Benchmark with its current version 4.0 is a GPU-intensive benchmark that hammers graphics cards to the limits. This powerful tool can be effectively used to determine the stability of a GPU under extremely stressful conditions, as well as check the cooling system’s potential under maximum heat output. It provides completely unbiased results and generates true in-game rendering workloads across all platforms, such as Windows, Linux and Mac OS X.” From Unigine.com.
The only issues with this VGA around OC’ing them lies on the heath sinker for the VRAM. They are cooled by air thereby if you OC’ way too much (like 400 to 700 Mhz) after a little even while GPU lies at 40-50 celsius, you’ll get artifacts.
What it is needed it’s a direct cooling unit for the VRAM aswell.