Question Getting black screen when a GPU is mounted on Motherboard

Jul 1, 2018
I have been having this issue since my computer arrived from my old home to my new one. It was transfered with a plane (2nd time) if that matter.The package was sealed and not opened at all.There was no sign of any damage.So when I tried to open my PC again I was getting a black screen with etheir "no signal" or a message at which channel the monitor was (DP or HDMI). I triple checked the cables or if by any chance anything was moved inside the PC, but I found everything just fine. So I starting doing the basics to find out the problem. I tried to connect my GPUto my monitor with the HDMI cable at first and same results. Tried with DP cable nothing changed. So I moved to connect the DisplayPort cable from motherboard to my monitor but the results were the same. So tried the HDMI as well but nothing.(Monitor was giving me the brand name when opened and worked as well at another PC) Even so I tried to check the same proccess with another monitor as well but the results were the same. So I started to changing the RAMs and see if that was the problem.Nothing changed and the problem remained the same. My last thought was to reset the motherboard by removing the battery and so I did. I had to unmount the GPU in order to do it. While was on that I thought to try and see if it will show anything without the GPU on, and SUPRISE it did. I was hoping it was because of the reset but when I mounted the GPU back on the problem came back. So I called the shop I bought them and they agreed to send them the GPU and test it out.The PC was working normaly without the GPU on. Then I found my older GPU and I tried to mount it and check something out. Well... the problem came back! So it seems that whever there is a GPU mounted on the motherboard it gives to signal from netheir the outputs(Motherboard's or GPU's) So my guess now is like the very first : it's a motherboard issue. I would like some help in case I missed something. Thank you in advance.Here are all the specs including Monitor and second GPU:

Palit GeForce GTX1080 8GB GameRock Premium NEB1080H15P2G EU
Corsair HXi Series HX850i 850W F Modular CP-9020073 EU

G.Skill TridentZ RGB 16GB DDR4-3000MHz F4- 3000CT6D-16GTZR x2

Intel i7-8700k 3.7 Ghz Coffee Lake EU BX80684178700K

MSI s1151 Z370- A Pro 7B48-001R EU

Monitor is BenQ
and 2nd GPU is GTX Geforce 650.

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