GA-Z270 Ultra-gaming stopped booting with GPU plugged in and powered

[outofcontrol]

MB: GA-Z270X-Ultra Gaming(rev.1.0)
BIOS: F8
GPU: ASUS RX580
CPU: i7-7700 BX80677I77700
RAM: Ballostix 16GB (2x8)
PSU: EVGA 700W
OS: Win 10 64-bit Build 1809

The problem:
PC worked fine since building in July 2018. Starting around January 26th 2019, PC would no longer boot, not even into BIOS, no Gigabyte splash screen. Lights on mother board come on and machine then sits idle - fans spinning. Lights on keyboard never came on. Unable to boot into BIOS.

After much testing, we found if we unplug the power from the GPU, and put the monitor on the MB, the machine would boot, but the screen is flickering/jumping/flashing/broken lines/distored in Windows. Booting into BIOS the screen is fine, and roaming BIOS all seems to work fine.

We tried a different GPU (NVIDIA 1080), and tried both GPUs in both PCIe slots, same results, machine would not boot. 

Tested both GPUs on a different computer using a GA-Z170 MB and all was fine.

We tried a different working EVGA 850W power supply, no boot. Reseated RAM, no boot. Different, monitor, monitor cable, no boot. Updated windows (was on 1803), no boot. 

Reset CMOS by power down machine, inplugging from wall, removing battery for 30 minutes. We would then boot into BIOS with monitor on MB and GPU not installed, put settings back for boot drive and OS version. Re-installed GPU... no boot.

With the RX580 in machine but no power added, machine would boot with MB graphics. 1080 in machine with no power added, machine would not boot at all. 

We suspect at this point there is an issue with the PCIe slots or motherboard in general.

Additional notes:
VAXG Voltage when in BIOS, sits at 0V. Is this normal?

 

[romirez]

Need to start from bios reflashing using programmer.

 

[outofcontrol]

Thank you for the suggestion. We've just now tried to update the BIOS with Q-Flash. The update went well and we are now on F9d. After updating there was no change in behaviour. We tried to reset the CMOS by removing the battery, inplugging the machine and waiting 15 minutes. No difference. We've now also tried a different HD, reseated the RAM again, and reseated the CPU. No difference.

 

[romirez]

Updating bios is not the same with reflashing.

 

[outofcontrol]

You are suggesting something different than this Gigabyte page suggests: https://www.gigabyte.com/webpage/20/HowToReflashBIOS.html

We did step one, but granted, it does say in the PDF "update". Everywhere we look for re-flash, it seems to point back to update. Would you have any suggestions on where to look so we can learn how to re-flash a BIOS?

 

[romirez]

Flashing bios using programmer - thats what service centers do.
Your mobo have soldered dual bios chips, so its possible they will need to desolder first.
Use service center.

 

[outofcontrol]

Mobo was fine. RAM was dead.