Right now Ryzen 3000 CPUs support 24 PCIE lanes - 16 for the GPU, 4 for a NVME drive, and 4 for everything else. That seems too low for for the enthusiast sector, so I'm wondering if the Ryzen 4000 CPUs will support more? A boost to 36 (16 for the GPU, 8 for two NVME drives, 4 for 10 Gb ethernet, and 8 for everything else) would work wonders. This would still leave Threadripper as the premium HEDT product with 88 (never mind Epyc's 128 lanes). This would also allow better product differentiation with the B650 boards supporting the basic 24 lanes and the X670 boards enabling 36.
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Will Ryzen 4000 CPUs have more PCIE lanes?
Soldato
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Does raid for NVMe work then?
It’s probably worth keeping in mind that it’s PCI-E Gen 4, but some current motherboards pretty much offer what you are looking for.
Soldato
Not going to happen and would have limited appeal. What portion of sales do you think Ryzen desktop enthusiast community uses more than 16+4 lanes? 1-2%? Add the additional 4x PCI-E 4.0 lanes the x570 chipset gives you, and this covers most of the requirements beyond that for those 1-2% of users. Then take the non-enthusiast sales which AMD are targeting as a way bigger overall % of total CPU sales, again using 20 lanes or less.
10GbE is only 2x PCI-E on 4.0, unless you need two full duplex ports.
What they should endeavour to offer is bifurcation on the boards PCI-E slots, and more variation of layout, along the likes of the Gigabyte B550 Vision D, and the Asus X570 Pro WS (which is a great board). This will allow the newer GPU's to run at 8x PCI-E 4.0, all that is required, and use the other 8x lanes for another slot or more M.2 devices, and beyond.
10GbE is only 2x PCI-E on 4.0, unless you need two full duplex ports.
What they should endeavour to offer is bifurcation on the boards PCI-E slots, and more variation of layout, along the likes of the Gigabyte B550 Vision D, and the Asus X570 Pro WS (which is a great board). This will allow the newer GPU's to run at 8x PCI-E 4.0, all that is required, and use the other 8x lanes for another slot or more M.2 devices, and beyond.
Yes. But that can be fully used, as the PS5 demonstrates.
Only the Epyc ones.
I think it would be pretty high, actually, if they were available. Remember that we're discussing the enthusiast market here, not the ordinary market, for whom I agree 16+4 is sufficient.
Soldato
So for the tiny % portion of the enthusiast market that uses more than 16+4 they should redesign the whole CPU?
Why not ask one of the mods to make this a poll and change the title, and lets find out how many people use more, or would want more if it meant spending more for an XE CPU, over the X version, so the 4700XE would be £399 but have 32+4 lanes (or similar), and the 4700X would be £299 but have 20+4 lanes.
Also you missed the last bit of my post, which illustrates you can get what you want with tweaked motherboard designs that are already in use by some manufacturers.
It is something I find annoying with CPUs these days - hence why I went with X79/4820K on my last build for the 40 PCI-e lanes.
(I'm currently using 28 for the record).
EDIT: Don't forget in many cases you get an extra 16-20 lanes provided by the PCH or PLX, etc. on many boards though that isn't necessarily a good solution depending on what you want.
(I'm currently using 28 for the record).
EDIT: Don't forget in many cases you get an extra 16-20 lanes provided by the PCH or PLX, etc. on many boards though that isn't necessarily a good solution depending on what you want.
How do you know that the Ryzen 4000 series doesn't aupport more lanes?
Soldato
Again ignoring the rest of my post. Maybe respond to what I have advised you with regards to lane layout.
If they shrink the I/O die down to 7nm they might be able to put more on it, as it will add a good amount of size to the die itself.
Thanks, that is good to know. So if your devices were PCI-E 4.0 you could be using only 14x/18x theoretically speaking of course. 8x on a GPU, then 4x/8x on two M.2 SSD's, and 2x on a 10GbE card.
Not with the B550 or X570 chipsets, you can't; only Threadripper and Epyc. The RX 5700 is already bandwidth-limited by PCIe3.
Except that we have PCIe4 NVME drives and PCIe4 GPUs so you cannot halve those numbers.
Soldato
yes nvme raid works, im running 3 nvme drives in raid0 at full speed on an MSI x570 Ace
And as other have said, you dont need anymore lanes from the CPU if you buy the right board, X570 comes with 16 full speed PCI-e 4.0 lanes from the chipset along with the ones from the CPU, giving a total of 40.
With B550 the lanes layout depends on the board, the Gigabyte master has 3 nvme slots, they are all wired to the CPU at PCI-e 4.0, along with the first GPU slot, if you use nvme slot 2 and / or 3, you GPU gets knocked down to x8 and the other 8 lanes get split to nvme slots 2 and 3.
Other boards are nvme slots are wired to the chipset and you only get PCI-e 3.0 out of those and loose something else along the way like SATA ports or the bottom x4 slot.
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The AM4 topology is flexible.
Yeah depends on your usage - IIRC X570 PCH only gives you 4x lanes at 4.0 bandwidth so you can easily use those up with one device alone.
Soldato
16 pal, but as 4 are for the uplink to the CPU you get 12, the chipset on X570 is identical to the IO chip in the CPU, only the chipset is 14nm and your IO in the CPU is 12nm, both made by GloFlo.
I thought the second 16 on x570 were from the PCH, not the CPU, and the PCH communicates to the CPU via a x4 link so it's really x4.were
Soldato
Again depends on the board, I have 3 x16 slots on mine, the bottom one is x4 electrical and thats to the PCH, the top two are direct to the CPU, use the first one you get x16, use both and you get x8x8.
Yes the chipset uplink to the CPU uses x4 PCI-e 4.0 lanes, but dont think of it a 4 lanes, think of it as bandwidth, so now you've got 16gb/s to play with, whats 2 nvme drives ? 10gb/s ? and thats only uplink, the downlink to the chipset uses 4 PCI-e 4.0 lanes from the CPU.
Don't think it works like that - you have upto 16 lanes (electrical) from the PCH but only a 4x PCIE 4.0 uplink from the PCH to CPU which might also be shared by other devices on the PCH.
Soldato
Ahh yes I see what you mean, but as I said in my last comment, dont think of it as 4 lanes up and 4 lanes down from the CPU, think of it as bandwidth, 1 x PCI-e 4.0 lane is 16GT/s, you now 64GT/s uplink and 64GT/s Down, that can easily handle 2 nvme drives and what ever else, there would be no other way to channel all that data at full speed from everything connected to the PCH back to the CPU.
MSI on the ace went for the 2 x 4.0 nvme drives and instead of the extra 4 sata ports, wired them to the bottom x16 slot (x4), it only has 4 SATA ports that come as standard.
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Soldato
So the boards that already exist, don't exist then, both the X570 and B550 versions?
The Asus X570 WS Pro-Ace is wired as follows "Three PCIe 4.0 x16 slots with optimized lane arrangement of 3-way x8/x8/x8 to accelerate an increasingly diverse array of workloads"
This means the top two slots are wired to support 8x PCI-E 4.0 devices, and the bottom slot is using the PCH lanes to make a single 16x slot wired to 8x PCI-E 4.0, with the limitation of 4x 4.0 speeds through the PCH. You also still have the full speed 4x NVMe 4.0 directly from the CPU, and a second M.2 slot that only has 2x 4.0 lanes, or the same speed as 4x 3.0 lanes when using a 4.0 drive, again limited if you are saturating the PCH from the PCI-E 16x slot.
Can you provide some evidence that the RX 5700 is bandwidth limited by PCI-E 3.0 when the RTX 2080 Ti isn't. Seems counter-intuitive that a slower card would require more bandwidth from the system bus.
The required bandwidth for a GPU is equivalent to 8x PCI-E 4.0 lanes or less until such time that much faster cards become available, and yes we have 4x NVMe PCI-E 4.0 drives, and I have added that in the number I posted if you noticed, I said 4x/8x lanes required for two devices. It is also depending on the speed or use of bifurcation on a PCI-E slot, as you can use a single 16x slot for 4x 4x devices when supported in the BIOS, or an 8x wired slot for 2x 4x devices.
More PCI-E lanes simply are not needed at the level of these CPU, however I would agree that they could offer a half-way house (assuming the I/O die would fit) on the high-end 12/16 core models, with a separate part number and design, if they feel they could justify the redesign, and offer it at a price premium between the TRX40 systems and the 'normal' AM4 boards.