The only hardware problem I heard discussed was that they shouldn't have required the PCIE Resizable Bar.
We know there's some sort of issue with idle power.
Having done some in-house firmware development, myself (not for any companies in this sector), it's almost certain there are chip bugs necessitating performance-robbing workarounds. That's what happens when you're not designing to an immutable ISA spec with a massive legacy codebase that you can't break. The hardware goes out the door once the
absolute show-stopper bugs are fixed or mitigated and the burden of any remaining hardware bugs falls to the firmware team.
I once had a chat with an AMD driver developer who confirmed they do indeed face these sorts of problems.
They could update PCIE4 to PCIE5 and get rid of Resizable Bar requirement. If their performance really is being limited by the CPU to GPU bandwidth, this seems like a no-brainer ... especially with the PCIE5 support already on Alder Lake and Raptor Lake.
Why do you believe PCIe 4.0 is a bottleneck? I've combed through Tech PowerUp's PCIe scaling analysis for the RTX 4090 and even the outliers gain < 10% by going from PCIe 3.0 -> PCIe 4.0 on such a fast card.
The new NVIDIA GeForce RTX 4090 is a graphics card powerhouse, but what happens when you run it on a PCI-Express 4.0 x8 bus? In our mini-review we've also tested various PCI-Express 3.0, 2.0 and 1.1 configs to get a feel for how FPS scales with bandwidth.
www.techpowerup.com
Also, consider how the RX 6500XT beats the A380, in spite of having a PCIe 4.0 interface only half as wide (also 33% less GDDR memory, not to mention a smaller die)!
If the A770 truly is being held back by PCIe 4.0, it suggests they're doing something wrong.