Quadro K6000 is Kepler architecture while the new Quadro M5000 and M4000 are second generation Maxwell architecture. This is the one that gamers will know of as Geforce GTX 980, 970 and so on.
The Quadro M5000 has a GM204 GPU and comes with 2048 Cuda cores. It has a boost clock capable of hitting 1050MHz and 6.6GHz GDDR5 memory with 256-bit bus and 8GB Video memory.
It supports 1/32 FP64 precision and has dual slot size. It max TDP is 150W. The Quadro M4000 has 1664 cuda cores and a GM204 GPU. The memory works at 6GHz with a 256-bit memory interface. The card has 6GB of the stuff. This is a single slot card with 120W TDP and it supports 1/32 FP64 precision.
Both cards support four 4K displays with 60 Hz refresh rate. Nvidia had a slight slow down in the Quadro business as the professional market depends heavily on the upgrade cycle. Nvidia sells most of these cards to movie makers and industry designers and almost every product designer had one of the Quadros.
AMD holds a smaller piece of the pie but Quadro has been one of Nvidia's best cash cows for ages.