Italian hardware site ReHWolution has received some early information regarding ASRock’s unannounced TRX40 Taichi and Creator motherboards. Apparently, they’re not backwards compatible with first- or second-generation Threadripper CPUs. Ryzen Threadripper 3000 won’t work on X399 boards, either.

The underlying reason between this restriction remains a mystery. We know that the EPYC “Rome” MCM is pin-compatible with first-generation EPYC “Naples” chips due to the fact that the newer chips are drop-in compatible with older servers via a BIOS update. The TR4 socket, too, is nearly identical to SP3r2, but for four out of eight memory channels being blanked out.