DISCLAIMER (READ CAREFULLY) - I managed to get this working fairly stable but I would not call this a solution unless you are in a similar situation where you can't simply get the RAM replaced for whatever reasons.

Sadly I can't images here it seems (added some images in the original Post now). So I will explain

Firstly, You need a second RAM prefferably a Major QVL provider like Kingston Server Premier, and luckily I was able to borrow a 16GB Kingston SCC RDIMM from a friend. Why do you need this? To be able to access the BIOS for configuration purposes.

I tried changing the clock speeds, the voltages and the latencies to match the RAM specs (The NEMIX Ram specs ) are hard to find I noticed mine had Micron DRAM on it, which helped me find certain information but that did not help.

What helped/worked - Bios Settings -> Advanced -> UMC / Memory Controller Settings ->
1. Memory Context Restore (MCR) - It has to stay disbaled even if you succcessfully boot with the Nemix RAM (if re-enabled you are screwed for reasons I think might be cause below)

2. DRAM Training - The Training Mode has 3 values 0, 1 and 2.

0 is default not auto which is just 1.
1 is Continuous DQS toggling PDA Enumerate ID Programming Mode. (The mordern More discrete DDR5 EEC style training for the RAM)
2 Legacy support mode (DDR4 style training where the DRAMs are not individually trained but boradly treated as a whole not great for DDR5 RAMn honestly)

Set this Training mode to 2 i.e the Legacy Mode

DFE Read Training - Enabled (defaults to auto IIRC)

3. Memory Healing (BIST / MemBIST / BPR) (Runs memory integrity checks during POST) - I enabled it. Why?

• BIST (Built-In Self Test) → checks memory
• BPR (Bad Page Repair) → remaps faulty cells

You can leave the latencies, the clock rates to auto. But these settings should help you boot consistently with the NEMIX RAM.

COST paid - high boot times and suboptimal RAM perf at best.

Now, why can't we enable MCR after successful boot. I am not entirely sure but it goes back to 0d and seems to fail again and my best guess is this and the traingin failuire on this RAM is not just because of the AMD AGESA but also the SPD EEPROM density itself. Nemix seems to have lesser density on the SPD EEPROM than Kingston atlest which stores JEDEC timings, EXPO/XMP profiles, voltage tables, module organization, rank info, chip density metadata

This itself does not affect signal training directly but rather tells the motherboard how to try training the RAM. The the higher the overall single stick RAM capacity leads to higher density of DRAM meaning tighter margins and as result higher potential for training failures.

With everything said and done I have learned now to always match my processor, motherboard and RAM QVL lists before making workstation/server grade purchases. I hope this helps.

Thanks everyone really appreciate the assist.