Re:Details on AMD's Quirky Chipset Solutions for AM5
by zamalek on Sunday May 22, 2022 @07:41PM
(#31473926)
This isn't really true for PCIe 4 and beyond. For example, if you use a competently manufactured PCIe 3 riser in a PCIe 4 GPU configuration then VGA will fail to POST more times than it succeeds (on the order of successfully booting 1/10), if it POSTs at all. Given how expensive PCIe 4 risers are most people choose to downgrade to PCIe 3 in the firmware settings.
Re:Details on AMD's Quirky Chipset Solutions for AM5
by AlphaSite on Sunday May 22, 2022 @08:50PM
(#31474305)
Are you sure this isn’t because of the tightened electrical tolerances for PCIe’s physical layer, not the protocol it’s self?
Re:Details on AMD's Quirky Chipset Solutions for AM5
by wmf on Sunday May 22, 2022 @08:34PM
(#31474221)
That's signal integrity not latency though.
Re:Details on AMD's Quirky Chipset Solutions for AM5
by cududa on Sunday May 22, 2022 @06:46PM
(#31473553)
Well the chipset also handles shuttling RAM channels..
Re:Details on AMD's Quirky Chipset Solutions for AM5
by NinjaKitten on Sunday May 22, 2022 @07:18PM
(#31473778)
No. You appear to have a fundamentally flawed understanding of the system at hand.
Re:Details on AMD's Quirky Chipset Solutions for AM5
by cududa on Sunday May 22, 2022 @07:26PM
(#31473836)
Perhaps. 16 years out from AMD ram/ cpu channel optimization. If the chipset isn’t handling RAM channels what component is?
Re:Details on AMD's Quirky Chipset Solutions for AM5
by wtallis on Sunday May 22, 2022 @07:31PM
(#31473858)
The DRAM controller has been on the CPU socket since AMD's Opteron/Athlon 64 (2003) and Intel's Nehalem first-gen Core i5/i7 products (2008). AMD's recent migration toward multiple chiplets on the CPU package has not changed the direct connection between DRAM and the CPU socket.
Re:Details on AMD's Quirky Chipset Solutions for AM5
by Laforet on Sunday May 22, 2022 @07:54PM
(#31474019)
>AMD's recent migration toward multiple chiplets on the CPU package has not changed the direct connection between DRAM and the CPU socket
This is true. However with the MCH off-chip and worst case inter core latency comparable a DRAM refresh cycle, AMD could in theory move the MCH away from the socket and see no major performance penalty.
Not to mention the Zen 2 IO die is just a cut-down version of X570, or maybe it is the other way around heh?
No, because PCIe works completely differently from RAM. PCIe is a packet-based protocol that's very latency-tolerant. (Multi-lane PCIe links may require deskew but that's a standard feature that has existed all along.) I think it was Marcan who tunneled PCIe over RS-232 and the chips didn't even notice.