1802 bios? I've had some strange memory issues since then too, maybe I need to enable MRC Fastboot vs auto...
Set trace centering to enabled.
I use Linpack to check my ram oc.
I tried 4266mhz on mine since I built it in 2018, slightly different kit than yours, but 1802 bios allows for XMP, but it fails memtest86 (unstable). I've managed to get significantly better timings at 4000mhz and better performance than what you posted at 4266mhz.
It seems like the issue was myself, not the hardware. Silly me, lesson learned, always load optimized defaults after making hardware changes.
I just loaded optimized defaults, activated XMP 2, set vccsa and vccio to 1.25v, maximus tweak mode 2, set tWRWR_dg to 4 (otherwise the MB will set it to 8 and in AIDA64 Cache And Memory Benchmark I get half of write speed on RAM).
After that, the memory looked like this and the MB trained the RTL and IOL values as following:
Values not seen in the above screenshot:
RTL (CHA) D0: 63
RTL (CHA) D1: 64
RTL (CHB) D0: 65
RTL (CHB) D1: 65
IO-L (CHA) D0: 7
IO-L (CHA) D1: 7
IO-L (CHB) D0: 7
IO-L (CHB) D1: 7
IOL Offset (CH A): 21
IOL Offset (CH B): 21
RFR Delay (CH A): 14
RFR Delay (CH B): 14
Everything was fine since then, no more stuck at debug codes, etc, after that I just had to work my other settings back.
The final problem was that my i9-9900KS was underclocked via offset since I was using the old DDR4 3000MHz and I had to work my CPU voltage a bit up for the system to always succes.
Final results, bellow:
My final question, are the RTL and IOL values properly training? I am worried about RTL 63-64-65-65. I enabled the MRC Fast Boot after it stabilized here.
Do I need to try to optimize timings further?
Thank you everyone in advance!