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Question about pcie lanes on Ryzen 3000

#1

The slides AMD showed on their events about the X570 showed on the left the Ryzen 3000 cpu. Which supports 4x USB 3.2 gen 2, x16 PCIe 4.0 for graphics, x4 for nvme and x4 as a connection to the chipset. All PCIe 4.0. Sofar nothing surprising.

But then the slide states “Pick one: 1x4 NVME OR 1x2 NVME + 2x SATA”. Now, hearing that Ryzen supports 24 PCIe 4.0 lanes all the time, this would mean 28. So I assumed this meant the x4 for NVME could be reconfigured for x2 plus SATA.

But Steve at Gamer’s Nexus in their latest video clearly states the Pick One option is additional to the 24 lanes. That seems wrong. I’m not even sure the AM4 socket has enough pins to support those extra 4 lanes.

So please comment on this, what’s with those extra x4 lanes?

Also, the slide states those x16 are for Graphics. If a motherboard splits these x8/x8 can you use one of those x8 for a RAID controller, or only for another graphics card? The information I could find about that is conflicting as well.

Please shed some light on this!

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#2

Aren’t those extra lanes provided by the chipset? So basically you’re talking to the chipset then the cpu? I think I heard Steve say they use basically a similar IO die to the one in the CPU in the chipset or something.

Well, that’s what I thought I heard anyway.

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#3

This, IDK what AMD calls it but its like DMI on intel.

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#4

There general purpose PCIe lanes, you can use them for whatever you want. hell you could even run a graphics card on one of those NVMe slots with an adaptor if you wanted to.

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#5

The extra lanes are provided by the PCH and in the case of AMD its connected via some sold IP called the Fusion Controller Hub… its similar but not the same as DMI…

I really wish though that they would put it on the infinity fabric so the branch prediction could be used for more tasks

PCIE lanes maybe divided as you see fit. There is no one way to do it. All graphics cards do fine on x8

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#6

No, it was when he was talking about the left part of the slide, about the lanes provided by the CPU. It’s this image: slide1

I hope the rumours of a X590 with more PCIe lanes are true. It’s too tight on the lanes budget with an X570.

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