Latest AMD AGESA firmware fixes bug that disabled cores on certain CPUs

We've known for a while that some dual-CCD Ryzen 7000 series chips can behave slightly strangely. For as yet unknown reasons, the first core of each CCD can often boot disabled, reducing the number of working CPU cores by up to two. Fortunately, this behaviour is limited to Ryzen 5 7600X and Ryzen 9 7900X processors using two “downcored” CCD chips, and a fix has just started rolling out.

The issue seems to lie with the AMD AGESA ComboAM5PI 1.0.0.4 firmware that uses the SMU (System Management Unit) 84.79.204. Fortunately, AMD and motherboard vendors (MSI and ASRock) were quickly made aware of the bugged SMU, which led to them removing the problematic firmware from the motherboard's support pages.

MSI put back AGESA 1.0.0.4 BIOS with new SMU 84.79.210. New SMU fixes boot issue with very few 6-core & 12-core Raphael CPUs that are "downcored" from 2-CCD chip, with both Core0 & Core7 disabled. pic.twitter.com/Ru8jScN7oY

— chi11eddog (@g01d3nm4ng0) January 12, 2023

As of now, the red team has already issued a fix via the updated SMU 84.79.210 to motherboard vendors (via chi11eddog) which should solve the problem. MSI has already updated its motherboard support pages to include the latest AGESA firmware using the new SMU update. Interestingly, although the SMU was updated, the AGESA firmware has retained the 1.0.0.4 version number.

From what we've gathered, MSI is the only motherboard vendor who has updated the support pages of its motherboards with the new AGESA firmware. Other vendors should follow suit soon.

KitGuru says: Do you have a Ryzen 5 7600X or a Ryzen 9 7900X CPU? Were you affected by this issue? Hopefully this update has resolved it now.

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