Thanks for using Apple Support Communities. You can switch to using the discrete graphics card by deselecting 'Automatic graphics switching' here:
"Automatic graphics switching" is enabled by default to allow your computer to automatically switch to the best graphics system for the applications running on your computer. Using this option may also maximize battery life. Deselect this option to use the higher-performance discrete graphics processor at all times.
Further Discussion Please!!!!!
Although there is a way to default UP (only use 750M) by going to:
Energy Saver --> Automatic graphics switching (unchecked)
My question is: is there a way to default DOWN -
A simple task like goog earth or a low quality video the Computer Auto Switches UP to the 750M when clearly Iris Pro can handle complex tasks - cutting the battery time in half (4 hours) - same with other use cases, such as: plugging in HDMI for broadcast - obviously Iris Pro can also handle - as base rMBP 15 models only have this GPU....
I want to use more IRIS PRO instead of the NVDIA Card!!!!! because is actually a good GPU!!!!! I appreciate good battery life like a MB Air