I have installed a slightly older graphics card, nVidia GTX 670, in the AORUS Z390 PRO WIFI mainboard.
When I turn the system on the CPU and DRAM checks pass, however the VGA light on the MB remains on. The system does not boot as usual, instead the usual booting screen seems to be skipped and the first screen that appears is the Windows login screen. The BOOT LED on the MB never comes on, and the red VGA LED remains on after startup and only stops shining when the system sleeps and then remains off after the system awakes from sleep.
Once the system has started it seems to run as usual.
What could the cause of this be? Is there away I can further diagnose the problem and perhaps fix it? Or is it likely to be a BIOS firmware compatibility issue, meaning a BIOS update will be necessary?
The mainboard was is running with the latest BIOS and the graphics card has the most recent driver.
Thanks for your help 
GIGABYTE AORUS Z390 PRO WIFI
NVIDIA GEFORCE GTX 670
INTEL i9 9900K
2 x KINGSTON HYPER X FURY 16GB 2666MHz
BEQUIET SILENT LOOP 240mm
BEQUIET 750W
(RAID 0 SYSTEM VOLUME) 2 x SANDISK FORCE 3 120GB
(RAID 1 STORAGE VOLUME) 2 x SAMSUNG EVO 860 1TB
Thanks for the detail and system specs. Unfortunately "latest" doesn't tell us what BIOS rev you are actually running. F9 was released 3-15-2019.
Regardless of this, none of the BIOS revs appear to address any video compatibility issues. Also Nvidia Gforce GTX 670 - is this an Nvidia branded card, EVGA, Gigabyte? Nvidia makes the chip, they made a reference design single blower card too, just need to verify.
Many 670 cards had FW updates which could help if yours was one of the affected models.
Things to look at:
See page 35 of your manual. Enable Fast Boot in BIOS. Now set VGA Support to Auto. (EFI is default). Save Exit and restart.
-Does this system start?
-Does the VGA LED stay on?
Just to be clear on one thing,
if you have Ultra Fast Boot enabled, change to
Fast.. this is
all you need. It would also explain why the first screen you see is the windows log in screen.
EFI (default) is what you want, but the card being as old as it is and with no FW update might be the cause. If you purchase a new or different card, be sure to change this setting back to EFI. Also change if the system won't boot.
See if there is a FW update for your specific card?
The 670 should be EFI compliant, but I cannot confirm this. Aggressive BIOS settings, overclocking or power would be the only other areas I can think of that might cause a problem.
Do you have another card (any) that you can test with?
