yup, my FTW does the same thing, doesnt boot without CSM compatibility.

AHowes
What is csm??

The Compatibility Support Module (CSM) is a component of the UEFI firmware that provides legacy BIOS compatibility by emulating a BIOS environment, allowing legacy operating systems and some option ROMs that do not support UEFI to still be used.

You thing about a GPU Bios to be Update? With some kind of specific one?

chaosminionx
I have CSM turned off on my R5E10 and SLI GTX 1080 FTW and no issues booting....
 
I can further elaborate as well:

CSM on it boots and shows the splash logo for Windows, and the R5E10 boot logo.
CSM off it boots and shows the splash logo for Windows, and the R5E10 boot logo.
 
I am using Displayport

You said the same thing happends for both on and off heh. ??

Try enabling csm & setting your pci-e lanes from auto to gen3 to see if it helps resolve the issue.

Sajin
Try enabling csm & setting your pci-e lanes from auto to gen3 to see if it helps resolve the issue.

Done yet, I will try other things tomorrow, Time to go to bed for me!

Hi
So Ive tried a couple of thing, CSM still need to be enable anyway on my RE10
I tried to put the 1080 on a MSI Z87 Mpower, which is configured without CSM, plus secure boot, Fast boot, And GPU is GOP ok, the boot work perfectly, even 4 sec to boot to windows. A shame that a i3 4130 on this old board can perform this boot speed uppon a brand new RE10/6850k couple. I think RE10 Bios has to be update to another one... I will try older bios! 
I'm open to other ideas :)

ElkossComb
Ok so I dont know Why but CSM can be disable now, boot ok and fast. I made a Memtest+ to check memory, as routine, and when I boot after that, It was fixed. I run it a couple of time, no instability, seems perfect!
I Used the GPU on a legacy mobo by the past. I'm questionning about some adaptative time to each bios on the new one, even if i'm perplex about it...
By the way I did not touch anything in new BIOS after Memtest+
 

I have the same issue on my 1080 FTW Hybrid, swapping the 1080 with another card, turning on the system, then shutting it down, then putting the 1080 back in temporarily solves the problem (it comes back after a while).

Hi everyone
So the problem kick again!
I tried Each Bios even Beta but:
After a fresh Bios flash, i reconfigure it correctly (XMP, etc) an put CSM off, then F10, and UEFI non CSM boot successful.
If I reboot it from Win, no problem either
But if I shut it down, an lauch after that: VGA led, 4 bips, and window pop 25sec later (vga led still on)
Back to Bios aft CMOS clean (because no possibility to access bios), enable CSM with std config, the boot is ok but longer.
I've got issues on few boot: no screen at all
EVGA support said that could be some incompatibility but I think there is maybe something more. 
Every other card work fine on this mobo, and my Gpu works fine with every other mobo I have the same way
I get mad^^
Even under CSM, it get me 4 hours to achieve the beginning of windows 10 install with my 1080
Problem not present with another gpu by the way
I did it 10 time per day at work, but this one on me!
Will try another 1080 to check it out
 
Regards

ElkossComb
Hi everyone
So the problem kick again!
I tried Each Bios even Beta but:
After a fresh Bios flash, i reconfigure it correctly (XMP, etc) an put CSM off, then F10, and UEFI non CSM boot successful.
If I reboot it from Win, no problem either
But if I shut it down, an lauch after that: VGA led, 4 bips, and window pop 25sec later (vga led still on)
Back to Bios aft CMOS clean (because no possibility to access bios), enable CSM with std config, the boot is ok but longer.
I've got issues on few boot: no screen at all
EVGA support said that could be some incompatibility but I think there is maybe something more. 
Every other card work fine on this mobo, and my Gpu works fine with every other mobo I have the same way
I get mad^^
Even under CSM, it get me 4 hours to achieve the beginning of windows 10 install with my 1080
Problem not present with another gpu by the way
I did it 10 time per day at work, but this one on me!
Will try another 1080 to check it out
 
Regards

Every other card work fine on this mobo, and my Gpu works fine with every other mobo I have the same way
I get mad^^
Are all the other cards Pascal Cards?
If not then maybe it is your Motherboard.

I dont even understand how I got my 1070, an M2 and two SSD's to boot correctly, but I know the CSM switch was something that perplexed me to no end lol

So with my HDMI 2.0a cable it works fine, but I'm limited to 50Hz on my 3440x1440 display (thanks to HDMI 1.4 build in)
Even with 1.2 DP or others 1.1 DP, same problem occurs... I'm gonna kill myself^^
I will keep going on CSM activated to get my 60Hz; 
Even with my 2nd GTX1080 the issue is present.
 
As my perf are perfect ingame, I will keep settings that way
So far so good!

http://www.clicktronic.com/nc/en/products/displayport/productview/displayport_kabel_casual/  
Seem to be ok at the time I bougt it. Do you think it can matter? DP 1.1 is ok for 3440X1440 @ 60Hz
I use to get HDMI 2.0 put my LG Widescreen 21:9 has only 1.4 hdmi input ( It will be up to 50Hz only)

Not all DP cable are truly certified -- Yes it does matter, if your having an issue I would check with certified cable
 
https://www.displayport.org/products-database/
 
 
Certified does not mean expensive.  This is what I use for 4K 60 Hz monitor and it is less than $20.00 USD
Accell B142C-010B-2 10ft UltraAV DisplayPort to DisplayPort 1.2 Cable with Locking Latches - 10 Feet
 
Amazon US Link
 
Accell Link