Recs.
Updated
3DMark is a cross-platform benchmark suite that specifically recreates gaming environments and is mainly a good method of testing your graphical card's performance.
SpecsUpdate
Pros
Pro Built-in stress test
A built-in stress test for 3D Mark was included in a free update which measures the stability of a system by looping a benchmark for a certain period of time. Shortly after, a stability report is generated. If 97% of the loops are successful, the system is stable enough for daily usage. The stress test is especially handy for overclockers who want to test their system's stability.
Pro Extremely thorough testing
3DMark offers multiple different tests and uses all the latest technologies to recreate the most intensive graphical situations. 3DMark is able to test your GPU and use a lot of different factors such as OpenCL and DirectX 11. There are also testing options available for low-end pc's and extremely high-performance systems with multiple GPU's.