TLDR; GPU raiser - RAM order is important!
I just recently returned from a trip to the USA and in the process of getting my work computer setup, I ran into a stressful and peculiar issue. I decided to bring my AMD Threadripper CPU and motherboard to the states to work, I could have just used a laptop, but since I was going to be there for at least 6 weeks I needed the firepower for a project we are working on (automated trading & machine learning). The system was working perfectly fine there and upon powering it up in a new case it did not work.
The motherboard is an ASUS Pro WS WRX80E-SAGE SE WIFI, CPU is a 3995WX (64-core beast). The new mobo is great, so many fantastic features and is more admirable than the equivalent WRX80 gigabyte motherboard (sans the thunderbolt!).
The Q-Code LED display kept on showing “02” after stabilising. This was frustrating as I could not visibly see any issues with the assembly and the fact that it worked in the states! I was going mad!
In the manual, the “02” error relates to AP initialization before microcode loading
As well as the white VGA light being on. I tried multiple GPUs that were working 100% still nothing.
I simplified the setup by removing all 256GB’s of RAM and inserting a single stick that I knew worked. I removed the GPU riser cable and after resetting the CMOS several times, it finally booted. I was surprised that both GPU raiser cables were giving me issues, as soon as I put the GPU on a raiser the motherboard did not like it and went into this odd compatibility state when removing the GPU raiser.
After validating the GPU raiser I had to insert each 32GB stick one at a time to ensure it booted. Sure enough at my 6th stick, it did not boot. I finally got the order right and it booted.
Disappointed that the system is so touchy but glad to get this up and running again. I do hope it helps someone who may have been in the same issue as me since I did not get a direct solution from google.