For several days I have worked with NetChain and NetTrain using the GPU with NetTrain. Everything runs quite well on my system and the results are impressing (performance). My system is equipped with two NVIDIA Titan Cards (linked together). Yesterday it seems like I have killed one of these Cards. Today I have purchased two new GTX 1080 (not Titans, but much more faster than my 4 year old first generation Titans). I have completely removed the drivers reinstalled everything and my computer runs faster than before (with 5 monitors attached). GPU-Test programs are running quite well showing the correct information (tests are showing that the new GTX 1080 are much more faster than my old Titans) BUT NetTrain (using GPU) now didn't work. While training, it shows a flat line for batch loss and round loss (nothing changed on the programs). And the result is an untrained net that gives untrained answers. Additionally I have completely uninstalled Mathematica 11 and I have deleted all files according to Mathematica, installed Mathematica completely new and tried it again. Problem is the same, NetTrain using GPU didn't work. It didn't crash, it simply did not learn. If I install CUDALink Mathematica shows correct answers (CUDA exists and Mathematica shows a great amount of GPU-Information). Only NetTrain didn't work (same code works using CPU). For me there are two options: 1) there are some kind of GPU-setup-information stored for NetTrain and I have not removed these information and it didn't work because the now non-existing Titans are used instead of the new 1080 2) GTX 1080 are not supported Any suggestions are highly appreciated, because it's boring using CPU-computing on a computer that's equiped with such an amount of GPU-power. Thanks for answers .