I picked up two of these used and after completing the build, I'm facing a symptom where the PC will only boot when there is something plugged into either the DVI or HDMI ports.  If the only thing plugged in is a DisplayPort, the machine hangs **after** POST when the windows load screen should show up. 
 
Just to make sure there's no question about what this means, the monitor turns on, shows me the bios splash screen with my ram capacity/speed, I can even hit DEL to enter bios and monkey with it, then save/quit etc.  It's specifically after POST that this hang occurs.  No amount of waiting, results in a successful boot.  Pressing the power button results in an INSTANT off, I don't have to press and hold like I would normally have to do during the windows boot process.
 
If, for example, I plug my TV into the HDMI port, then power on the machine, it will boot windows just fine, initially showing the windows load screen on my tv, then switching to the DP monitor shortly after.  Once booted, the machine has no problems with any of the DP ports.  I've tried booting off every DP port on BOTH of the two cards, and they all behave the same on boot.  Likewise, both cards behave exactly the same.
 
I've found some posts around the internet explaining that this is a DP boot order issue for NON UEFI based motherboards, and the system I put together for these is indeed a legacy x58 system with a regular BIOS.  I found a 1080ti DP updater tool that I had hoped would fix the issue, and it did flag both cards as needing an update, and updated them both successfully.  The same post where I found the link to the nvidia custhelp page with the 1080ti DP updater tool mentions that their GPU also needed a BIOS update to fix the problem.
 
I took a look at the techpowerup bios database and it seems there is only one BIOS available for the 1080ti SC2(the same that is on both of the cards I have).  
 
Based on the ease in which I found several posts describing this exact problem(and also how I was tipped off to try the HDMI/DVI ports), I'm hoping there's a bios floating around out there that I can obtain to address this problem.  This is somewhat of an issue since the monitor for the system in question, an original PG278Q, ONLY has a displayport.
 
Thanks in advance!
 
Edit: I did register them and also have submitted a request to the support department.
Edit2: Just realized there is a stickied post in this forum about this specific issue... It says you only need the updater tool, but I've confirmed it's the same tool I downloaded before(downloaded it again anyway and ran it on the system, and it says no update is needed) https://forums.evga.com/D...-on-Boot-m2832050.aspx

Thanks for the followup

I have added a Note, to the post you mentioned in your first post, to mention the old BIOS issue you ran across

zoson
For sure!  Another update is I bought a $5 HDMI dummy plug and it works around the problem.  No need to run a super long HDMI cable every time a reboot is necessary.
 
This does make POST invisible(since the PC thinks it's posting to HDMI instead of DP), but as soon as windows loads the screen flips over to the DP just like it did with the TV.  But if I need to get into bios or see a POST error I can just unplug the dummy plug then.

Great workaround