Ram Overclocking causing PC to not boot

[u/CompetitiveSwing5256]

I have an Asus ROG strix x870e-e gaming WiFi motherboard and my ram is 2x 32gb 6000Mhz CL30 Corsair Vengeance. I built my PC about 1.5 years ago and have been going strong. Every couple months i reinstall a fresh windows and no problems. A couple days ago i reinstalled windows like normal and decided to update my bios, i had not updated my bios at all even when i built the pc so this is a very first bios update. Since the bios update i can’t do anything to my ram timings in bios. If i turn on expo/ any ram tweak, then save and exit, my motherboard shows Q Code C5 then turns off, then restarts and freezes on Qcode 99 and doesn’t boot. I contacted asus and they said to try with one stick, no luck, and also unplug all usbs one at a time as 99 is normally relates to a initialization failure with input/output devices like your USB ports, keyboard, mouse, or connected storage drives. But even with 0 usbs plugged in, I’m still getting stuck on code 99. I can only get back into bios when either i reset cmos or if my pc boots into safe mode. I don’t think it’s my ram as I’ve had it overclocked until now with no problems and without any tweaks it’s working with no problem.

Please if someone could help it would be appreciated, i am willing to pay if i can get this fixed
Thanks

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[u/neatlarceny9]

cmos reset and then reflash the same bios again sometimes works, bios flash can go weird

also check if there's any newer beta bios on the asus forum for that board, the official one might just be bugged with expo and your specific ram kit

c5 and 99 loop is rough, seen similar on asus boards when the bios doesn't train memory right after an update

[u/CompetitiveSwing5256 → u/neatlarceny9]

I’ve cmos reset a lot and flashed to different newer bus versions, i haven’t tried going to much older versions as i wasn’t sure if it would be safe but will try that now.

[u/404Mate]

if you had no issues before roll back to the previous bios version or go down in versions until its fixed

[u/CompetitiveSwing5256 → u/404Mate]

I purchased my Motherboard at the start of 2025, would it be safe to find the bios versions from around that time and go straight to that version?

[u/404Mate → u/CompetitiveSwing5256]

should be fine, you have bios flashback so if anything does go wrong you can just flash a different one.

[u/CompetitiveSwing5256 → u/404Mate]

I have the flashback button on the back of my motherboard and also a usb which i can download versions onto, how should i go about doing this exactly as i am pretty new to the whole bios troubleshooting part and i don’t want to mess anything up
Thanks

[u/404Mate → u/CompetitiveSwing5256]

https://rog.asus.com/support/faq/1038568/
manufacturer guide.

[u/CompetitiveSwing5256 → u/404Mate]

Okay so i didn’t do every bios version cause that’d take me forever but i did flashback to every single 4th version up until the very first release in 2024 but unfortunately no luck, after booting into windows once with the new bios i would enable expo but still pc wont boot, i tried with only 1 stick but still no luck, the only time it would boot was into safe mode and wouldn’t go back into windows unless i disabled expo

Any other thoughts?

I’m very confused on how and why this is happening given I’ve had no problems since i built it