Sunday, June 16th 2019

AMD B550 and A520 Lack PCIe Gen 4 Capabilities?

Last Friday, we reported ASMedia working on new-generation socket AM4 motherboard chipsets that succeed the AMD B450 and A320, which could hopefully offer significantly cheaper alternatives to boards based on the feature-rich AMD X570 chipset. The DigiTimes story we cited was updated to clarify that the chipset only supports PCI-Express gen 3.0, and not the newer PCI-Express gen 4.0. There are two distinct ways of interpreting this information.

One, that motherboards based on B550 and A520 completely lack PCIe gen 4.0, including the main PCI-Express x16 (PEG) slot and the M.2 slot wired to the AM4 SoC; and two, that only the downstream PCIe lanes and the chipset bus are PCIe gen 3.0, while the main PEG slot and M.2 slot from the SoC remain gen 4. We lean toward the latter interpretation being more plausible, that AMD B550 and A520 motherboards will at least feature one PCI-Express 4.0 x16 slot, and one M.2 slot that has PCI-Express 4.0 x4 wiring from the AM4 SoC; while the ASMedia chipset is connected to the SoC over PCI-Express 3.0 x4, and downstream PCIe lanes put out by the chipset are gen 3.0, too. These ASMedia-sourced AMD 500-series chipset motherboards could also implement the latest PCB, CPU VRM, and memory wiring specifications released by AMD that enable CPU and memory overclocking levels unattainable on motherboards based on older chipsets.
Source: DigiTimes
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13 Comments on AMD B550 and A520 Lack PCIe Gen 4 Capabilities?

#1
Metroid
If the b550 lacks pcie4.0 and has no feature worthy to wait for then is a waste, simple enough.
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#2
btarunr
Editor & Senior Moderator
Metroid, post: 4065839, member: 178915"
If the b550 lacks pcie4.0 and has no feature worthy to wait for then is a waste, simple enough.
Please read the article. I argue that motherboards based on these chipset will have partial gen 4 (i.e. the PCI-Express x16 slot and topmost M.2 slot will be gen 4).
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#3
TheLostSwede
btarunr, post: 4065840, member: 43587"
Please read the article. I argue that motherboards based on these chipset will have partial gen 4 (i.e. the PCI-Express x16 slot and topmost M.2 slot will be gen 4).
Most likely correct.
Also, expect improved 400-series boards with better support for the 3000-series CPUs. Still no PCIe 4.0 support of any kind though.
Might be worth keeping in mind for those looking at getting 400-series boards now.
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#4
windwhirl
I imagine that it would be a nightmare for AMD to say "Yes, our Ryzen 3000 CPUs support PCIe 4.0, but no, you can't use it all without a X570 motherboard". They wouldn't even bother making new chipsets if that were the case.

At the very least, I think that PCIe 4 will be available for use at the main slot or for NVMe. Either that or the bandwidth will be usable in some other way.
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#5
Metroid
TheLostSwede, post: 4065843, member: 3382"
Most likely correct.
Also, expect improved 400-series boards with better support for the 3000-series CPUs. Still no PCIe 4.0 support of any kind though.
Might be worth keeping in mind for those looking at getting 400-series boards now.
Too long to wait, not worth the time, b450 is looking to be the only alternative day by day. x570 is only worth for the 16 cores cpu.
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#6
turbogear
I think I will stick with my ASUS Crosshair VII WIFI and only upgrade to 3800x/3700x from 2700x depending on how much gaming performance increase one of these will offer compared to 2700x.

I am satisfied with Crosshair VII. PCI-E 4.0 at the moment is not relevant for me. Radeon VII does not need that. :rolleyes:

For data and NVMe , I don't think I will change my current setup.
I own one 250GB Samsung 970 Evo Plus NVMe drive for Windows plus all programs.
Two Samsung 1TB Evo 860 are used for games plus data.
Family videos and photos are on two Raids 3TB each controlled by a PCI-E card from Dawicontrol DC-624e. :D

For memory I am not sure at the moment if much difference in performance will be seen in reviews between DDR-3200 CL-14 and DDR-3600 CL-16 for example.

I am using a good sticks of 16GB G.Skill DDR4-3200 CL14 Trident Z from AMD version (F4-3200C14D-16GTZRX).

My current system: ;)

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#7
TheDeeGee
I just wonder if these Motherboard come without a small fan.
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#8
medi01
5700/5700XT are listed as supporting PCIe4, by the way.

I wonder, what effect it could have on gaming.
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#9
turbogear
medi01, post: 4065977, member: 158537"
5700/5700XT are listed as supporting PCIe4, by the way.

I wonder, what effect it could have on gaming.
I don't think it will have any difference.
5700XT is not faster than 2080TI.
As far as I know 2080TI is not saturating PCI-E 3.0.
So I don't expect any performance difference.
We should get some reviews on 7th of July at launch date.
Hopefully also some comparison for PCI-E 3.0 versus 4.0 on Navi.
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#10
bug
It's like, once AMD got Intel on the ropes, it's now simply backing away. They simply didn't need this entirely self-inflicted debacle.
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#11
MAXLD
If B550 boards don't pack any suppport for PCI-E 4.0, then they'll be mostly useless (vs. B450) for anyone going for a 3600X / 3700X ... unless the B550 memory support is much better. If a typical proper B450 board doesn't fancy straight forward DDR4 3600 XMP profiles (which is apparently the sweet spot for Zen 2), then B550 might have a chance to justify the waiting.

All things considered, real market launch prices for the X570 most affordable boards will be the key. At the 170~200 range, I might bite the bait instead of waiting for B550 / buying B450.
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#12
TheLaughingMan
I don't see a reason to build the board to not have PCIe 4.0 at all. Correct me if I am wrong, but the direct traces to the AMD CPU that would drive the directly connected x16 and x4 slots for GPU and single M.2 slot use need to meet specs for the throughput. It seems like it would be more work to build it in a way where it would not meet spec for the direct traces to only support up to PCIe 3.0.
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#13
DeathtoGnomes
its basically like getting a hotdog that you ordered with everything on it and it only has condiments on half of it.
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