Nvidia’s Geforce Titan is widely used in industry for deep learning and video processing tasks. It is more precise in most cases. More detail on the performance of the GTX line (currently GeForce 10) can be found in Wikipedia, here.
Nvidia’s Quadro GPU isn't for scientific computation, you can use Tesla GPUs for that.
Quadro cards are designed for accelerating CAD, so they won't help you to train neural nets. They can probably be used for that purpose just fine, but it's a waste of money.
So I suggest using GeForce Titan over Quadro for deep learning. It's being commonly used in industry for deep learning They are really fast and precise.
Hope this answer helps.
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