Tesla K80 cannot work properly in Ubuntu 14.04

We have installed two Tesla K80 GPUs for computing, but they are always out of work after we login into Ubuntu for a couple of minutes. The states of both K80 are OK in the beginning, but the error state would soon appear (in “nvidia-smi” command). And we can see that the temperatures of K80 are extremely high before they go out of work. The motherboard we are using is ASUS X99-E WS. Can anyone tell us where the problem is? Is the motherboard incompatible or the cooling system far from satisfactory (currently two fans above them)?