This Codes I get if I restart PC but mainly D6 if PC has to be restarted. But if I shutdown system than all runs fine and no D6 beep sounds are heard. I know PC needs make up it's mind on what is wrong "RIGHT!" anyways I have run windows memory diagnostic that went Fine. Ran Prime 95 that went fine no lock ups nor freezes Temps got to be 69* C and test was still running smooth. Like I said full shutdown seems to fix this  Codes 03-04 come rarely but come at times. I have read about them but still perplex to what is going on.  D6 means no gpu detected. The beeps could be due to how many usb devices you have plugged in. Windows running fine all apps run fine and Games run fine no problems with anything it seems related to GPU performance fan come on fine on GPU.  Ok about MOBO is and RMA replacement and I check it very well there no damage to it at all there was not even scratches were you place screws to secure motherboard to PC case. so This let's me know is brand spanking new. I did CMOS reset since gave me a CMOS issue few times when i started few times and make sure I reinstalled new copy of Bios. Check all connections they are all seated properly check GPU is seated correctly too. All this codes but when I use PC all seems fine no crashes no hang ups no freezes. Ran Aida64, HWiNFO64 latest ones and all seems well. Has anyone come across this issue I have scouted the net and read  alot about it but seems there solutions don't give 100%.

agent_x007
Restart in Windows 10/11 means actual shutdown and start again, "shutdown" in Start menu of Windows 10/11 by default means Hibernation/Sleep (unless you disabled it via command line) - Fast Boot comes from here.
So, if above is correct, your PC is having issues while trying to start from nothing.

Is this EFI/GPT boot, or are you using MBR/Legacy boot ?
Check if there are firmware updates for GPU, or try to use it on different slot ?

Hibernation is fully disabled never use it. I also have fast boot disabled in bios too. GPT is a New NVMe SSD where I installed Windows 11 Pro directly to it. If I shut down fully D6 code seems to go away.