I recently completed a build with a Z690 and started having a set of strange issues right after power up:
 
1st: Initially the system would not post. A manual (USB + BIOS button) Flash and update of the BIOS to the latest version was conducted.
This resolved the No post issue. I was able to enter the BIOS
 
2nd: After leaving the default optimized settings as is, I saved and exited, then the system would not Boot from my SSD. Multiple times the system restarted and attempted to enter Windows RE, unsuccessfully. Either the "Classified" splash screen would pop up with the throbber and possibly a description. Sometimes it would just hang up and restart.
 
I was able to get it to boot from the SSD after adjusting the XMP to Profile 1 6200 MHz (4400MHz was the default). This booted state lasts between 10 seconds and 2 minutes. The system shuts down and goes back into an attempted Boot loop. The system must be hard reset to stop the loop. Entering BIOS again allows it to Boot again.
 
I am able to Boot to Windows Safe Mode and it will idle in safe mode without resetting.
 
Other diagnostics and work around attemps that I've made include:
-Attempting to Boot with only 24 pin, dual 8 pin CPU power, and water pump. Same result.
-Re-arranging RAM (normally using slot 2 and 4 as per manual), tested with every conceivable configuration for 2 sticks and 4 slots.
-Removing and reseating the CPU 4+ times, inspecting the MOBO and CPU contacts each time.
-Memory test was run via cmd prompt in Windows RE. Normal test settings revealed 0 errors.
-BIOS versions used: 1.15, 1.14, 1.10, 1.05, 1.04, 1.03
-The in-bios CPU Stress Test runs for 10+ min without issue (4700 MHz, 1.17-1.125 V, 55-65 C), shut down will trigger during OC Robot
-In the brief times that Windows is booted: CPU temps are 25-35 C at idle, Task manager reports 5-15% CPU usage (similar for RAM) with no spikes before the shut-down.
-Shut down will occur with no known trigger. Will trigger at the login screen or literally anytime. No uptime is longer than 2 minutes though.
-The associated Boot drive works perfectly on multiple other systems even my MS Surface 4 can run it from a USB Boot.
 
 
I am at the end of my expertise without messing with a bunch of over or underclocking, seeing as the system can't handle default settings. I'm hoping somebody has some magic to get this so I don't have to do a bunch of RMAs, which would be a first in like 15+ years of using EVGA products.
 
Thank You kindly for your time!

Since you can idle in safe mode... sounds to me like you need to do a clean install of windows onto your ssd instead of using an old install of windows on a new build. OC robot can cause your system to crash/shutdown if the oc is unstable.

Thank you for the suggestions. I did get similar feedback from tech support.
 
After your suggestion, and because there is nothing like a faulty PSU to make you feel like a Noob, I tried swapping out the PSU with two separate PSUs, a 1000W and a 750W from Corsair. Same result on both though.
 
Also checked the 3.3v 5v and 12v rail voltages in BIOS and they are stable +/-5%
 
When I was in Safe Mode Event viewer there were Category "Critical" events that said the system had shutdown improperly. The only events before hand, I assume before each crash was; a Warning event that a device had input incorrectly and just before that a warning that the ethernet was not connected (never has been). I can't access the event viewer anymore though or I'd recall the codes. See below.... 
 
I did a full clean reset/install of Windows 11. It installed fine, but now I can't get through the initial Windows 11 onboarding setup (region, language, keyboard, etc). It crashes the same way as it was.
 
This evening I just received a brand new 12700k. Swapped it in. Same result.
 
I had definitely played the game of adjusting the cold block, the spring loaded screws from an EK block, with a back plate, will never tighten as much as the board CPU bracket does though.
 
The only thing I can point to is that this $630 MSRP motherboard might as well be a frisbee.   
 
Dissapointing. 
 

Friend, if you can post your resolution of this case, I would really appreciate it. I'm not really having problems, but any solution is very welcome to the community. Thanks