Se você tem uma placa nVidia, o RivaTuner é o seu melhor aposta. Você pode monitorar a memória gráfica e as velocidades de clock do processador, você pode fazer overclock de seu cartão gfx, personalizar DirectX, OpenGL e mais.
RivaTuner is a complete powerful tweaking environment, providing you everything you may need to tune NVIDIA GPU based display adapters. The widest driver-level Direct3D / OpenGL and system tuning options, flexible profiling system allowing to make custom settings on per-application basis, both driver-level and low-level hardware access modes, unique diagnostic and realtime hardware monitoring features.
A nVidia também oferece suas próprias ferramentas:
NVIDIA PerfHUD is a powerful real-time performance analysis tool for Direct3D applications. PerfHUD is widely used by the world's best game developers and was a 2007 Game Developer Magazine Frontline Award Finalist.
e este está disponível para Windows e Linux:
NVIDIA PerfKit is a comprehensive suite of performance tools to help debug and profile OpenGL and Direct3D applications.
It gives you access to low-level performance counters inside the driver and hardware counters inside the GPU itself. The counters can be used to determine exactly how your application is using the GPU