Wrong resolution in UEFI setup menu

dzsc wrote: Sorry, I mispelled it, edited the original text to off. So, finally I disabled the CSM.

Thank you for the clarification.

When CSM is enabled, the UEFI firmware is operating in emulated legacy BIOS mode, which limits it to the capabilities of BIOS firmware. We also don't have the UEFI Graphics Output Protocol (GOP) working. The VBIOS of older video cards don't support GOP, and we will get a black screen, at least until the OS starts and the video driver takes over. Normally POST detects that, and stops the PC from booting. That's one of the main reasons CSM is enabled by default.

I want to add this from your first post:

dzsc wrote: Finally I turned the csm on off, and the wonder happend, both the bios and the boot screen are full hd :) So give it a try!

The part I want to point out is including the "boot screen", which means the display we see before the OS boots, like the ASRock splash screen, POST messages, etc, that is not part of the UEFI UI display. I think that is what you mean, right?

I've also seen differences in the resolution of the POST/boot screen display, depending upon the type of connection between the video card and monitor, DisplayPort, HDMI, etc. But then I noticed something else...

I only noticed this when I had multiple monitors connected to video cards that have multiple types of outputs, and more than one output of the same type. A new EVGA 1060 video card I have has three DisplayPort outputs, one HDMI, and one DVI-D. I have three monitors connected to it, that are shared with multiple PCs, so it's a mess of different cables from each PC to the monitors.

I noticed that the three DisplayPort outputs are not the same regarding which monitor is active during POST. Depending upon which DP output I used, the monitor receiving a signal during POST (only one of the three will be active) would be the monitor connected with the DVI cable, instead of the DisplayPort cable. That would also be the monitor that was used if I was using the UEFI UI. Again, that also would be different (different monitor and resolution) if the CSM option was enabled or disabled.

It's a complex situation that I don't completely understand yet. The point I'm trying to make here is, if your video card has multiple outputs of the same type, and you see different resolutions in the POST/boot screen and the UEFI UI, try changing to a different output of the same type. As dzsc said, if you can set CSM to disabled, that can also make a difference.

Great solution!

I had the same issue. After testing some RAMs I tweaked the BIOS (MB: X370 PRO4) and accidentally enabled CSM. After that however I set BIOS UEFI HD, GRUB, whatever, the resolution went to VGA.

After reading your post CSM was set to off and all OK Full HD!

So thanks!