AMD Ryzen 9 9900X CPU Fails with Physical Substrate Swelling

A Reddit user reported a sudden AMD Ryzen 9 9900X processor failure accompanied by physical swelling on the underside of the chip. The owner, posting under the name u/TheImmigrantEngineer, stated that the computer suddenly refused to boot or POST. The motherboard displayed a Code 00 error code and lit the red CPU debug LED, indicating a critical hardware failure.

Alternative angle of Ryzen 9 9900X CPU contact pads with blister.
Side-profile angle showing the elevation of the substrate blister on the contact pads.

After removing the CPU and cooler, the builder discovered a distinct bubble-like blister protruding from the center of the bottom contact pads. The top metal integrated heat spreader (IHS) of the processor appeared completely normal with no signs of thermal damage. The motherboard socket pins corresponding to the swollen area also showed signs of compression from the physical pressure.

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The owner was using an MSI MAG X870E Tomahawk WiFi motherboard running a BIOS updated in early 2026. While the hardware was running at stock voltages with no manual overclocking, the user did enable Precision Boost Overdrive (PBO). Other platform parts included a 240 mm DeepCool AIO liquid cooler and a Corsair RM1000X power supply that later tested fine in another setup.

MSI MAG X870E Tomahawk WiFi motherboard AM5 socket.
The AM5 socket on the MSI MAG X870E Tomahawk WiFi motherboard where the CPU failed.
Close-up vertical view of AM5 socket pins.
Inspection of the AM5 socket pins on the motherboard.

Hardware failures involving physical swelling are not entirely new to the AMD AM5 platform, which is also used on budget motherboards like the Colorful iGame B850M Ultra V14. In a prior incident, AMD initially denied a warranty claim for a swollen Ryzen 9 7950X3D before reversing the decision after public pressure. The owner of the failed Ryzen 9 9900X CPU plans to submit a return merchandise authorization (RMA) claim to replace the damaged chip.

Source: Reddit

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