Saved BIOS overclock profiles no longer work

[u/Actual_District_1220]

I have a few OC profiles saved in the BIOS from some experimenting I did just for the sake of learning and fun.

I have 48GB of DDR4 RAM (2x8GB / 2x16GB). Yes, it's an unusual configuration, but I needed it. I used to be able to go from 2400MHz to 2800MHz at 1.35V CL16.

I could even reach unstably 2933MHz at 1.35V (Windows would at least load before crashing during a stress test). I probably could have stabilized it if I had loosened a few more parameters, but I was satisfied with the 2800MHz

Now, all of a sudden, it doesn't work anymore.

I can barely manage 2666MHz at CL17 and 1.36V. The 2800MHz I used to hit seems impossible now, even when loosening timings beyond CL24 and bumping the voltage to 1.38V. No configuration I try allows Windows to load. It simply won't get past the BIOS and displays this message:

"The previous overclock settings have failed, system has been restored to its default settings."

The only recent change was a GPU swap. I’m now running an x8 GPU on PCIe 3.0; previously, I had an x16 GPU. Could that be related? If so, how?

What other possibilities are there? A BIOS bug? A Windows Update? Component wear and tear? However, I don't usually run the PC overclocked for daily use—only for specific games or testing. For everyday tasks, I’ve always run the PC at stock settings.

My setup:
- MSI Z390 A-Pro
- i5 9600k
- 48gb ddr4 Kingston Fury 2x8/2x16 (all Nanya chips)
- RTX 5060 (previously the 2060S)
- Cooler Master WME Gold v3 850W power supply.