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EXPO suddenly stopped working after 6 months — 9800X3D + B850 + DDR5-6000 CL30
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EXPO suddenly stopped working after 6 months — 9800X3D + B850 + DDR5-6000 CL30

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EXPO suddenly stopped working after 6 months — 9800X3D + B850 + DDR5-6000 CL30

I need some help figuring out what is actually failing here.

System:

  • CPU: Ryzen 7 9800X3D
  • Motherboard: ASUS TUF GAMING B850-PLUS WIFI
  • BIOS: 1686
  • RAM: Goodram DDR5-6000 32768MB PC5-48000 (Kit of 2×16384) IRDM Black (IR-6000D564L30S/32GDC)
  • GPU: RX 9070 XT

The strange part is that EXPO worked perfectly for about 6 months. I played games with EXPO enabled without any problems.

Yesterday I removed my GPU from the PC and installed it back. After that, EXPO suddenly stopped working. The GPU itself works normally, and I also tested using the CPU's integrated graphics with the same result.

With BIOS defaults, Windows boots normally at 4800 MT/s.

I also tested the RAM sticks individually — neither stick can boot with EXPO enabled.

Here is the interesting part:

If I disable EXPO and manually set DRAM Frequency to 6000 MT/s, while leaving the timings/voltages on Auto, the PC boots into Windows normally.

ZenTimings in this configuration shows approximately:

  • 6000 MT/s
  • MCLK 3000
  • UCLK 3000
  • FCLK 2000
  • Auto timings around 48-48-48-96
  • DRAM voltage around 1.10V

But if I enable the actual EXPO I profile (6000 CL30-36-36-36, 1.35V), the system fails POST and the motherboard gets stuck on the Boot LED.

I already cleared CMOS and tested again.

I also tried some manual timing/voltage adjustments. They improved things somewhat, but TM5 still eventually produced errors — one configuration after ~2 hours and another after ~55 minutes.

So I'm confused about what is actually failing.

Why would 6000 MT/s work manually with loose Auto timings, while the EXPO profile that worked for 6 months suddenly refuses to POST?

Could this point to:

  • RAM degradation/failure?
  • CPU IMC degradation?
  • motherboard/BIOS memory-training issue?
  • something related to the physical GPU removal/reinstallation?
  • or simply one of the EXPO timings/voltages suddenly becoming impossible for the IMC?

I would really appreciate advice on what to test next without going through dozens of manual timings one by one.

Thanks!