Been running a 1070 for a couple of years in my Dell Aurora desktop. 16 gigs of ram, 1 tb HDD, 460W power supply. Upgraded to a 2TB SSD, had to remove the video card to do that. Reinstall and I get a black screen. Check all of the connections and lo-and-behold I had connected the power cord wrong; it is a 6 + 2 connector and I had forgot to add the +2. I'm not sure which holes I slotted it into. Reconnected correctly but still black screen. Tried all display outputs, tried moving PCIE slots, nothing.
 
I ended up using the onboard UHD graphics, running over the same DP cable to my monitor, to clone the HDD and set up my SSD. Checked the BIOS, no settings to turn on or affect PCIE. The 1070 has fans running, but the system does not recognize it at all, shows nothing in the slot under device manager, cannot install drivers.
 
I find an old gtx 670 and plug it in to the PCIE slot. The system recognizes it, I install new drivers, it works just fine using HDMI.
 
So...PCIE slot seems to be working. DP cable and monitor working. Online wattage calculators say that I should have enough power. Did I screw the 1070 up by plugging in the power cable incorrectly?

The 6-pin connector can only be inserted a single way, so I don't see how forgetting to plug in the extra +2 pins could harm anything.

Update: the card is indeed unusable after trying a new PSU. Found a used 2070 Super that works just fine. I believe that connecting the 6÷2 connector without the +2 and powering it on may have been the culprit; it's the only action that was at all out of the ordinary. Thank you ty_ger07.

kougar
I don't understand why they would change how the GPU was wired that way. So if the card thought nothing was plugged in it would fry itself, which is I guess what happened here. That's a very shoddy design if so... 

It should not fry itself.  It absolutely should not.  It should just give a constant unchanging warning message on the screen saying to power off the computer and plug in the power connectors.
UNFORTUNATELY though, there have been 2 or 3 examples within the last month of people reporting this exact same failure immediately after accidentally booting up the computer with the power cables disconnected.  Why?  I have no idea.  But it has been happening.  Very odd for sure.  The very unfortunate thing is that I can't find those threads now.  Oh well.