Blu-ray playback and a GPGPU test
Both AMD and NVIDIA have dedicated logic on their GPUs that offloads much of the computational work required when processing high-definition video.
A £60 add-in card is faster at converting video formats than a £140 CPU. Both discrete cards reduce the Core i5 750's time by around 35 per cent. Interestingly, it wouldn't run on the Radeon HD 4550, even with the Avivo package reinstalled.
Running hardware encoding through the GPUs also reduces CPU load from near-100 per cent to, on average, 55 per cent.
