Hey all, I have been a long time lurker but now needed to reach out for your expert assistance. I recently purchased a used GTX 1080 that I was assured works, and so far am unable to get it to work. Here are the details and the behaviours. GTX 1080 Gigabyte Windforce OC 1080 Gigabyte x370 gaming K5 (Latest Bios) 16gb Flare X DDR 4 3200 Ryzen 1700 (no OC) 600 w OCZ power supply. I have used this system since Ryzen came out with an R9 290 and recently decided to upgrade. When I put the card into the system and boot, the fans and lights all come on as normal. The LED indicator on the bottom right of the motherboard does not signal any errors with the VGA, RAM, CPU or BOOT. When the boot light goes dark, it tells me that the computer has made it into windows. I can also tell because the fans will ramp up and slow down. While this is happening, I do not have an image on my monitor. Through the post, I do not see bios options or the Gigabyte Aorus Logo. When the computer gets into Windows (as seen from the boot light going dark), then the screen changes from "no signal" to "resolution is 640x480/60hz" the standard you are not at native rez line. The problem is that even while this resolution message is on, I am only seeing an illuminated dark screen. I have tried Clearing the CMOS. I have reseated the video card several times. I have tried using a different 8 pin power connector and modular slot on my 600w PSU. By putting an older ATI 5750 into the primary PCI-E slot, I was able to boot into windows with the GTX 1080 in a lower PCI-E slot. In Device manager, Windows recognized the card as a 1080 and I was even able to install geforce drivers. When the computer restarted going back into device manager the message was that "Windows has stopped this device because it has reported problems (Code 43)." I am thinking next step I take it apart to look for obvious signs of damage (caps or thermal paste problems) and then maybe try to reflash the bios. Has anyone ever had anything like this before? The seller assures me that the card works, but I have very little recourse at this point if it does not. Thanks for any and all help you can provide. As a side note, when I reinstall the R9 290, everything works as it used to (minus the cleared CMOS settings).