AMD just explained on OC3D.net why there are 4 dies on AMD Ryzen Threadripper 1950X. In reality the 4 dies would not have 8 cores each as suggested by der8auer on Youtube with his video which showed a decapsulation of the processor and revealed 4 dies. It was then believed in all logic that Threadripper had a total of 32 cores, that half of them were deactivated and that finally it was a recycled AMD EPYC 7601. This would have allowed AMD to save money on building chains.
In reality, the processor would have 4 dies, but two of them would be empty, their presence would allow better dissipation of heat according to AMD.
AMD has retrieved the SP3 socket of the EPYC processors, but the presence of the two additional diagonal dies only allows to support the capsule to withstand the pressure of the dissipator, such as pillars and to better evacuate thermal energy.