What txbob said. A few simple things to check:
[1] GPUs without active cooling (that is, without an integrated fan) require a server-type enclosure that provides adequate airflow across the passive heat sink. Sticking a passively-cooled GPU into a regular workstation case will cause overheating in as little as 30 seconds. Luckily the GPUs have sensors and shut themselves down when that happens, so permanent damage is avoided. Placing GPUs with active cooling inside a server enclosure can also be problematic as the airflow paths (case vs GPU) likely don’t harmonize. As far as I know, all K80s are passively-cooled devices.
[2] Make sure the GPU is firmly seated in the PCIe connector to ensure both signal integrity and power delivery (PCIe card can draw up to 74W through the connector, according to spec); if possible avoid riser cards. If there is a fixation mechanism (e.g. a screw that fixates a bracket on the GPU to the case) make sure that mechanism is engaged. There are various sources of vibrations in PCs and servers that can cause plug-in devices to wiggle out of their connectors over time.
[3] Check all auxiliary power connectors. Many GPUs have simple 6-pin or 8-pin PCIe power connectors (or both); I believe the K80 has a more advanced power connector, don’t recall what it is called. Usually the connectors have tabs designed to snap into place once the plug is inserted completely, make sure that is the case.
[4] Make sure the power supply unit (PSU) provides sufficient wattage. As a rule of thumb you would want the total rated wattage of all system components combined to be 50%-60% of the rated wattage of the PSU for optimal robustness and efficiency. Use of an 80 PLUS Platinum rated PSU is highly recommended (some recent servers may come with a 80 PLUS Titanium PSU, which is the most advanced kind of power supply currently available and a tad superior to the Platinum class). A useful overview of 80 PLUS rated PSU can be found here: [url]80 Plus Overview | CLEAResult