Crap. Updated windows, restarted, completed update. Shut down PC. Turn off the PSU. Remove the GTX 970 Insert the GTX 1660S Plugged the HDMI in. Turned on the PSU. Power on the PC. PC running, nothing shown on the monitor. Waiting, waiting, nothing. check the GPU, fans not spinning any more. Shut everything down. Check the cables and try again. Same result. No error signs shown on the motherboard. Unplug the power connector on the GPU and plug a different one. Nothing changed. Changed slot. Same. Cleared the CMOS. Nothing. Put back the old GPU. No signal going to the monitor... Changed monitor and HDMI cable. The new monitor also doesn't show anything...even with the old GPU. That was about 2am last night. Pissed off I leave it and go to bed. This morning I power up my old lenovo laptop (it has a GTX 860m) and plug in the (normal) monitor. No signal detected. I stand there perplexed. Different systems, different monitors, different cables, how can they experience the same exact (bad) results? Am I in a twilight zone episode? I power down and up again the main monitor. It powers up, it shows the BenQ logo etc, but quick goes in sleep more with no signal detected. I go into the monitor's menu (small joystick in the back for the OSD). I check the input options and it sees the cable and has it selected. I re-select it. Monitor "connects" and now shows me the Lenovo's desktop. But this can't be it. Because I tested a different monitor too. WTF is going on? After I post this and have breakfast, I am going to put the new GPU in the original slot, try again and see if doing the same thing fixes it. If it doesn't fix it I might burn the whole thing down. If it does fixes it, then I have no idea what is going on, again.