https://www.techpowerup.com/245603/a...xpress-gen-4-0

The "Vega 20" silicon will be significantly different from the "Vega 10" which powers the company's current Radeon RX Vega series. AMD CEO Dr. Lisa Su unveiled the "Vega 20" silicon at the company's 2018 Computex event, revealing that the multi-chip module's 7 nm GPU die is surrounded by not two, but four HBM2 memory stacks, making up to 32 GB of memory. Another key specification is emerging thanks to the sharp eyes at ComputerBase.de - system bus.

A close inspection of the latest AMDGPU Linux driver includes PCI-Express link speed definitions for PCI-Express gen 4.0, which offers 256 Gbps of bandwidth per direction at x16 bus width, double that of PCI-Express gen 3.0. "Vega 20" got its first PCIe gen 4.0 support confirmation from a leak slide that surfaced around CES 2018. AMD "Vega" architecture slides from last year hinted at a Q3/Q4 launch of the first "Vega 20" based product. The same slide also hinted that the next-generation EPYC processor, which we know are "Zen 2" based and not "Zen+," could feature PCI-Express gen 4.0 root-complexes. Since EPYC chips are multi-chip modules, it could also hint at the likelihood of PCIe gen 4.0 on "Zen 2" based 3rd generation Ryzen processor family.