Metalklesk System Monitor Crystal is a SuperKaramba theme modified from the System Monitor Crystal Clear theme and nvidiaGPUsensorsV0.3 theme, in fact is a fusion but with some changes (it doesn't need nvclock for Nvidia cards to take the data).
You can adjust it just editing .theme file with your favorite text editor (e.g. Kate).
This version is in Spanish only, but it's very easy to change to your language.
You must have installed Nvidia propietary drivers (nvidia-settings is used by this theme) if you want to see Nvidia GPU data (like core frequency, memory frecuency, etc).