AMD's new Ryzen 7 9800X3D processor has thick dummy silicon that uses 93% of the CCD stack, provides no performance benefits, and is completely non-functional, but it's required for stability.

On previous x3D processors, the 3D chiplet was stacked on top of the CCD (Core Complex Die) which allowed the cores direct access to the pool of additional L3 cache memory, but AMD moved the 3D chiplet underneath the CCD for the new Ryzen 7 9800X3D.

In a recent teardown of the 9800X3D, Tom Wassisk analyzed the CCD of the 9800X3D and found that most of the silicon on it is... rather useless. The CCD and SRAM silicon layers measure 7.2µm and 6µm respectively, with the total die stack and interconnects, etc measuring only 40-45µm.

The total CCD is around 800µm thick, leaving 750µm of silicon layers... the thick layer doesn't have any functional parts, sticking to the stack in order to improve the structural support, providing more protection to that precious 9800X3D processor.