Not always heat related. People here had issues with weaker power supply from Topton failing memtest.So, my conclusion is this: The memory issues mentioned by many people here are most likely due to overheating. DDR5 runs very hot and cannot withstand constant memtest load.
As a solution, I placed a 7mm(5mm+2mm) thermal pad between the motherboard and the RAM. I have seen a similar solution in laptops from MSI, where they place thermal pads between the SSD and the motherboard. This cooled the RAM by 15-20°C (!) and works great.
I didn't have heat issues but installed this ram copper heatsink fins for extra cooling. Although, I think the 8010 PWM fan was enough to cool things.
Here are other extras I bought.