Ryzen 9 9900X CPU reportedly dies with visible substrate swelling

A Ryzen 9 9900X owner has reported a sudden CPU failure on the MSI MAG X870E Tomahawk WiFi motherboard. The system stopped posting and showed a Code 00 error with the red CPU debug LED lit.

The user “TheImmigrantEngineer” says the CPU and motherboard are both less than one year old. The system used a Corsair RM1000X power supply and a 240 mm DeepCool AIO cooler. According to the post, the PSU was tested in another system and worked without issues.

Small bump under the CPU

After removing the cooler and CPU, the owner found a small physical bump on the underside of the processor. The bump is located near the center of the contact pad area. The IHS reportedly had no visible damage, and the thermal paste spread looked normal.

The user says the system was not using manual voltage tuning or manual overclocking. However, Precision Boost Overdrive was enabled in the BIOS. That means this was not a fully default configuration, even if there were no manual voltage changes.

Source: TheImmigrantEngineer/Reddit

The BIOS version was not listed, but the owner claims it was from early 2026. In a follow-up comment, the user said the BIOS was flashed between late January and early February. That is the key detail here, since this was not an old launch BIOS from the first months of AM5.

We recently covered a similar case , although it involved a different CPU. In that case, AMD initially rejected the Ryzen 9 7950X3D warranty claim, but later reversed its decision after media backlash. Hopefully, the new case will be handled more smoothly for the Ryzen 9 9900X owner.

Source: Reddit

AMD Ryzen AM5 CPUs with visible swelling are not a new problem. However, there was no confirmed root cause, and there is no evidence that the motherboard, CPU, BIOS, PBO, or another voltage rail caused the failure. The owner plans to RMA the processor.

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