The Third Generation Ryzen Threadripper CPU announced last week are not compatible with the TR4 socket of the X399 motherboards. AMD introduced a new socket, sTRX4, And a new chipset called TRX40.
Consequently, even the previous Ryzen Threadripper cannot be installed in the new TRX40 motherboards with sTRX4 sockets. All this despite the two sockets the same pin number, 4094. This created some moodiness among those interested in building an AMD workstation, and for this reason the company intervened to better explain its decision.
The problem is that the two sockets they are electronically incompatible. According to AMD, pin mapping for voltage and data is different. The good news is that the sTRX4 socket will not be replaced soon, in short, AMD will plausibly keep it for some time.
“There are two reasons for this choice,” AMD wrote in a post on Reddit. “First, we wanted to get maximum performance and sTRX4 helps us do exactly that. Secondly, the socket change also prepares us for it future development and scalability of the Threadripper platform, both short and long term“.
As already explained, the third generation Ryzen Threadripper platform offers a total of 88 PCIe 4.0 lines, of which 72 usable (CPU and motherboard). Threadripper 3000 processors in themselves offer 48 PCI Express 4.0 lanes.
In particular, between the CPU and the chipset there are 8 PCIe 4.0 lines, while in the past there were 4 PCIe 3.0 lines. This allows AMD to quadruple the bandwidth between CPU and chipset and consequently users will be able to use many more devices connected to the chipset at maximum performance.
AMD plans to support the sTRX4 socket for many years to encourage enthusiasts to purchase TRX40 motherboards. From this change, at least the platform is expected to remain stable for three generations of Threadripper (one more than TR4 / X399), therefore three years if AMD will maintain the current development cadence.
It will be interesting to see what will happen with the advent of DDR5 memories and PCI Express 5.0, which will almost certainly require a new socket. At this point we can expect a new socket for Threadrippers in 2022.