As always, we'll begin with a few theoretical performance benchmarks to get a rough idea for how the cards will perform. First up, 3DMark 11 which uses a multitude of DirectX 11 functions like tessellation, DirectCompute and multi-threading to put a card through its paces.
Both overclocked GTX 680s showed some improvement over the reference model, however gains were not all that substantial, with MSI beating the reference design by just 2% and Palit by just 4% on the Performance Preset. We did see some improvement on the Extreme Preset, with Palit outscoring the NVIDIA model by 10%, and MSI by 7%.
In the tessellation heavy Unigine 2.1 "Heaven" benchmark we saw similar results, with MSI's GTX 680 outperforming the reference model by about 4% across all settings and resolutions and Palit by about 6%.
NVIDIA's GeForce GTX 670 was actually the best performer on this benchmark, but this may be due to its newer drivers - ForceWare 301.33 - whilst only ForceWare 301.10 drivers were available for GTX 680 models at time of testing. Take note of AMD's Radeon HD 7970's very strong performance in this DX11-heavy test benchmark, which even the overclocked GTX 680 cards couldn't unseat in certain test settings.