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Wrong resolution in UEFI setup menu

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dzsc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dzsc Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jun 2017 at 5:02pm
Sorry, I mispelled it, edited the original text to off.

So, finally I disabled the CSM.
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parsec View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote parsec Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jun 2017 at 11:40pm
Originally posted by dzsc 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:

Originally posted by dzsc 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.
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salomonfr View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote salomonfr Quote  Post ReplyReply Direct Link To This Post Posted: 10 Dec 2018 at 8:21pm
Same problem here. Asrock z370 exreme4 and msi gtx 1060 gb gaming x using display port. I disabled CSM. Now resolution is good in boot but wrong (small) in bios. What I can try to do? Or it is an Invidia ussue?
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