We are expecting to see AMD’s 3rd generation Ryzen Threadripper HEDT processors launch in November. We’ve heard that AMD will actually be launching three different chipsets with these processors (TRX40, TRX80, WRX80). It turns out at least the TRX40 chipset will not be compatible with 1st and 2nd generation Ryzen Threadripper processors. Upcoming 3rd generation Ryzen Threadripper processors will not be backwards-compatible with the AMD X399 chipset either. ReHWolution has tweeted that upcoming TRX40 boards from ASRock are not compatible with 1st and 2nd generation Threadripper processors.
ASRock TRX40 Taichi & Creator coming in November. Not backward compatible with 1st and 2nd Gen Threadripper CPUs. Also, 3rd Gen TR CPUs won't work on X399 boards.
— ReHWolution (@ReHWolution) October 9, 2019
The reason for the chips not being compatible is sort of a mystery right now. We do know that the EPYC “Rome” MCM is pin-compatible with first generation EPYC “Naples” chips since newer chips are drop-in compatible with older servers via a BIOS update. Both the TR4 and SP3r2 sockets are nearly identical too except for four out of the eight memory channels being blanked out. I guess we’ll find out the reason for the chips not being compatible in November when AMD is expected to launch their 3rd Generation Ryzen Threadripper processors.