B450 Gaming-ITX/ac+ 3600 no POST on 10.50

I had no issues with any of my AM4 boards and 10.50 (or latest update with
security keys) with my 3600. I used the same CPU to update:
X370 Taichi
X370 Gaming K4
X570 Taichi
X570 Pro 4

Given the update will contain the same AGESA across all AM4 boards I doubt it will
be different from one model to the next. Support for the 3600 was not dropped.

Based on what you describe, it seems like the system was struggling with RAM
training after the update. I would try just giving it a bit more time. Power on
with the 3600 and leave it on for 10 - 15 mins and see if it POSTs. If not, try
using just one stick of RAM in slot A2 and clear CMOS before powering on.

Sometimes after a BIOS update the first POST can take longer on some CPUs. I suspect
the same issue for both the 3600 and the 5600. I am almost certain both would
eventually POST.

Let me know how it goes

Edited by Xaltar - 27 Apr 2026 at 3:18am

Thank you Xaltar and eccential for your suggestions - it is appreciated.

I attempted the following:

1. Installed the 3600, powered on for 30 minutes but the system did not POST.
- I did a CMOS reset
- Only 1 RAM stick was installed (there's A1 and B1 on this board, I installed in A1)
- System turns on, CPU fan spins, CPU fan turns off, system turns off and the cycle repeats.

2. Tried same thing with the 5600. System did not POST after waiting 30 minutes.
- CMOS reset, 1 RAM installed in A1
- System turns on, CPU fan turns on and system stays like this (system does not power cycle like the 3600).


3. Installed the 5500 and system POSTS within minutes with no issues. CMOS reset was not necessary.

4. I updated the BIOS to P10.50 (again) using the 5500 and a different flash drive. 5500 POSTS no issues.

5. I installed the 3600 again after a CMOS reset and like before, system did not POST. (same symptoms as before)

6. I tried the 5600 as well but no luck. Same symptoms as before, system did not POST.


@eccential:
By ROM being corrupted, I assume you mean the BIOS? (pardon my lack of knowledge)
That is why I reflashed BIOS P10.50 again in step 4. Unfortunately this did not make a noticeable difference.
The differences you highlighted between 3600/5600 vs. 5500 sticks out. Do you think something on the motherboard got damaged or corrupted, which a BIOS update won't fix, that is preventing IOD side initialization? (for both 3600 and 5600) Is this possible?

During my attempts, only a USB keyboard was plugged into the motherboard. No other USB peripherals.

Correct, I am not seeing a boot screen or ASROCK logo. USB keyboard lights also don't turn on, so system doesn't reach the state where USB power is enabled.

The 9070XT was a recent upgrade from a few months ago :). I was planning to upgrade the CPU/motherboard/RAM later since RAM prices are so expensive now. But now this problem has me reconsidering.

I did try rolling back the BIOS to P4.80 using the R5-5500. Was unsuccessful.
- 3600 with P4.80: failed to POST, same symptoms as before
- 5600 with P4.80: failed to POST, same symptoms as before
- 5500 with P4.80: POSTs immediately with no issues

I chose P4.80 because I can be sure it supports the R5-5500. I worry if I roll back too far, I might lose support for the 5500.
Now unfortunately, even with BIOS P4.80, the 3600 failed to POST.

My theories:
1. Maybe rolling back BIOS versions is not as simple as I thought? Maybe there's some attributes of the AGESA that can't be rolled back?
2. The 3600 CPU got damaged? Although I think this is unlikely.
3. Or something on the motherboard got corrupted or damaged - making it incompatible with the 3600 / 5600. Maybe something to do with the memory controller on the IOD side? This seems to be the most likely theory so far.


To summarize:
- 3600 was working originally on P5.20. After updating to P10.50, system failed to POST.
- 3600 and 5600 now fail to POST on both P10.50 and P4.80 (it is expected to work on both)
- 5500 will POST with no issues on both BIOS versions.