That doesn't pass a sniff test at all. The 7950X3D TDP is 120W vs. the 7950X's 170W, even ignoring that modern TDP is a dumb metric actual power consumption als

That doesn't pass a sniff test at all. The 7950X3D TDP is 120W vs. the 7950X's 170W, even ignoring that modern TDP is a dumb metric actual power consumption also backs that up - the 7950X3D uses signiifcantly less power than a 7950X. And, as an expected result of that, the 7950X3D also runs cooler as a result than the 7950X does. There's no evidence to support a thermal or power limit here. And it wasn't that different for the 5800X vs. 5800X3D, either. The extra cache at the same TDP seems to translate to around a 200mhz clock speed loss, temperatures otherwise the ~same. Cache is also not very power hungry in general. Perhaps you meant it was a thermal barrier but again see above - all evidence points to AMD having figured that part out, there's no hint of thermal constraints on either the previous nor current 3d v-cache parts.