By: tacobell (vasco.costa.delete@this.gmail.com), August 6, 2022 5:51 am
Room: Moderated Discussions
Bill K (bill.delete@this.gmail.com) on June 14, 2022 5:33 pm wrote:
> I suppose it’s possible that the higher-voltage transistors, mixed-signal tranceivers and I/O pads could
> have a different defect density than the core+cache. My guess would be no because most of that area (DRAM
> controllers, PCIe controllers, Compute Express Link, Ultra Path Interconnect) is logic that will have a similar
> defect density to logic in the CPU core. A defect in a DRAM controller would make a tile unsellable because
> there are no part numbers with different numbers of DRAM controllers per tile. So it’s much worse to have
> a defect in a DRAM controller than a CPU core, even if the defect density in both are the same.
Bill. AMD Zen's architecture is like it is.
They use a lower density design "uncore" in the middle.
I/O does not need as high density processes and often consists of mostly large contact pads.
If you use a lower density process, which likely has better yields, and has less demand, then you get better cost effectiveness this way.
> I suppose it’s possible that the higher-voltage transistors, mixed-signal tranceivers and I/O pads could
> have a different defect density than the core+cache. My guess would be no because most of that area (DRAM
> controllers, PCIe controllers, Compute Express Link, Ultra Path Interconnect) is logic that will have a similar
> defect density to logic in the CPU core. A defect in a DRAM controller would make a tile unsellable because
> there are no part numbers with different numbers of DRAM controllers per tile. So it’s much worse to have
> a defect in a DRAM controller than a CPU core, even if the defect density in both are the same.
Bill. AMD Zen's architecture is like it is.
They use a lower density design "uncore" in the middle.
I/O does not need as high density processes and often consists of mostly large contact pads.
If you use a lower density process, which likely has better yields, and has less demand, then you get better cost effectiveness this way.
