PCIe 4.0 wont be supported on B450, X470 and older chipsets

[porina]

Quote

The AMD X570 platform will be the first fully PCIe 4.0 compliant mainstream platform but existing AM4 motherboards such as the ones based on the X470 and B450 chipset would also be open to supporting the new PCIe standard when paired with a new Ryzen 3000 series processor & updated to the latest BIOS.

https://wccftech.com/gigabyte-bios-update-pcie-4-am4-motherboards-amd-ryzen-3000-cpus/

 

While it has long been known that PCIe 4.0 support will come with the new chipsets, there is now suggestion that some older ones could do so also after a bios update after references to PCIe 4.0 were found in recently released bios updates adding support for future processors. It still requires a Zen2 CPU to support it, but this could be a nice extra for those looking to update CPU on their existing mobos. Until more devices support it, it wont mean a lot but could give these platforms a little more life looking forward.

 

Edit 21 May:

https://www.anandtech.com/show/14364/gigabyte-am4-motheboards-pcie-4-ready-for-ryzen-3000

Above shows PCIe 4 option in Gigabyte bios.

 

Edit 3 Jun - now reported that older mobos will NOT get PCIe 4.0 support: see https://linustechtips.com/main/topic/1065402-pcie-40-support-on-b450-x470-with-bios-update-and-zen2-cpu/?do=findComment&comment=12616591

 

 

 

 

[williamcll]

I wonder how this will affect PCI-E lanes.

[porina]

Just now, williamcll said:

I wonder how this will affect PCI-E lanes.

If you mean how many will be available on the existing mobos, I can't see how it would change anything as they're fixed. On new 500 series models they might have more scope to redirect resources around.

[schwellmo92]

10 minutes ago, porina said:

If you mean how many will be available on the existing mobos, I can't see how it would change anything as they're fixed. On new 500 series models they might have more scope to redirect resources around.

The chipset lanes would still be 3.0, only the CPU lanes would be 4.0.

[porina]

43 minutes ago, schwellmo92 said:

The chipset lanes would still be 3.0, only the CPU lanes would be 4.0.

While we await more details, the indication is only the CPU lanes to the first slot will be 4.0. 

[Doobeedoo]

Quite cool though. Can't wait t see faster SSDs heh. 

[Trixanity]

56 minutes ago, porina said:

While we await more details, the indication is only the CPU lanes to the first slot will be 4.0. 

Not according to the leaked Biostar specs although they aren't fully written out so there's a chance they aren't running at the same speed.

[porina]

5 minutes ago, Trixanity said:

Not according to the leaked Biostar specs although they aren't fully written out so there's a chance they aren't running at the same speed.

Got a link? Haven't seen that and unable to find it.

 

For a board designed as such, I was thinking it would be interesting to have two PCIe 4.0 8x slots from CPU as that would give the same bandwidth on each as 16x 3.0.

 

I did forget that one of the M.2 which is CPU connected could go to PCIe 4.0 also. Shall have to wait and see if they can do that on older mobos also. It would be interesting to see if SSDs can hit 8GB/s  

[Trixanity]

16 minutes ago, porina said:

Got a link? Haven't seen that and unable to find it.

 

For a board designed as such, I was thinking it would be interesting to have two PCIe 4.0 8x slots from CPU as that would give the same bandwidth on each as 16x 3.0.

 

I did forget that one of the M.2 which is CPU connected could go to PCIe 4.0 also. Shall have to wait and see if they can do that on older mobos also. It would be interesting to see if SSDs can hit 8GB/s  

There you go. There will be 1 x4 m.2 slot from the CPU and 2 x4 m.2 slots from the chipset.

[The Benjamins]

16 minutes ago, Trixanity said:

There you go. There will be 1 x4 m.2 slot from the CPU and 2 x4 m.2 slots from the chipset.

On updated 400s boards I would expect the chipset link and chipset lanes to remain the same gen. With only 500s getting the speed bump.

[Trixanity]

2 minutes ago, The Benjamins said:

On updated 400s boards I would expect the chipset link and chipset lanes to remain the same gen. With only 500s getting the speed bump.

Of course. They can't retroactively change the chipset so it'll be a bottleneck in that regard but I would assume any new customers would go for 500 series chipsets anyway.

[porina]

39 minutes ago, Trixanity said:

There you go. There will be 1 x4 m.2 slot from the CPU and 2 x4 m.2 slots from the chipset.

Looking back I think we had crossed intent here. I was talking in particular about adding 4.0 to existing 400 series chipset boards. Also the link doesn't exactly confirm or deny the 2nd CPU slot will be 4.0 on 500 chipset. I hope 500 chipset would offer that, but it may be less likely on a 400 chipset was my original intent.

[mariushm]

The cpu has 24 pci-e lanes coming out of it. They can be pci-e 4.0 or they can fall back to pci-e 3.0

One of the requirements for pci-e 4.0 is maximum length between cpu and device ... if I remember correctly it's 10 inches or 12 inches... basically less than 30 cm - and that includes the distance on the video card between the actual slot and the chip on the card.

 

The pci-e x16 would probably work in pci-e 4.0 mode if you insert a 4.0 device as that's close to the cpu.

However, the chipset being further away, and not being aware of 4.0, would probably negociate with the cpu and downgrade the link to pci-e 3.0 x4. As the pci-e x4 link going to m.2 is probably grouped with the x4 going to chipset, the m.2 connector would probably also be downgraded to 3.0 even if it's close to cpu.

 

The maximum length can be increased with retimer chips but they're expensive... unless you're gonna get a high end board most motherboard makers won't bother.

 

AMD seriously needs to figure out how to make a "less than 570" chipset fast, one which doesn't need an active fan to function ... the fan adds to cost and lots of people want fully passive computers or super silent ... a 40mm fan (or whatever) will be anything but silent.

 

[Trixanity]

24 minutes ago, porina said:

Looking back I think we had crossed intent here. I was talking in particular about adding 4.0 to existing 400 series chipset boards. Also the link doesn't exactly confirm or deny the 2nd CPU slot will be 4.0 on 500 chipset. I hope 500 chipset would offer that, but it may be less likely on a 400 chipset was my original intent.

Yup, definitely. I was thinking of 500 series boards when posting. I can see now that the thread is about existing boards. My bad.

 

I think 4.0 support will depend on the quality of each board so I think we might see varying degrees of support depending on what board vendors can or will validate.

[porina]

19 minutes ago, Trixanity said:

I think 4.0 support will depend on the quality of each board so I think we might see varying degrees of support depending on what board vendors can or will validate.

Exactly. When making new 500 chipset mobos, they will be designing for 4.0. With 400 chipset, were they forward looking enough for that? Or are 4.0 requirements close enough to 3.0 that it would work most of the time anyway?

 

To me I see this as a nice to have, than a need. We don't have any 4.0 devices yet do we? So it will take a bit of time for that to build up. Personally I'd always want the latest chipset to go with a CPU if possible so this wont be a major factor to me... unless Zen 2 is so much better I really do decide to stuff one in every AM4 mobo I currently have.

[Drak3]

Just now, porina said:

We don't have any 4.0 devices yet do we?

If you're looking to blow $700+, the Radeon 7 uses the PCIe 4.0 bus.

[porina]

2 minutes ago, Drak3 said:

If you're looking to blow $700+, the Radeon 7 uses the PCIe 4.0 bus.

I will look forward to Navi then. Or whatever is post-Turing.

 

Think it will be more interesting in the storage space, not that anything I do can really use up to 8GB/s transfers.

[WereCat]

1 minute ago, porina said:

To me I see this as a nice to have, than a need. We don't have any 4.0 devices yet do we?

Its a big deal even if we dont have PCIe 4.0 devices because you can still take the advantage of having twice the amount of bandwidth.

 

Especialy for Chipset bandwidth this is a huge deal because now you can run multiple NVME SSDs and USB devices just from chipset without hitting the bandwidth limits like many people do right now, me included. And I dont even have a single NVME SSD. I am hitting the limit just from all of my USB devices connected.

 

For most people it doesent matter if you run your graphics card from PCIe 3.0 or 4.0 as they tend to just use one card anyway so there is plenty of bandwidth for them. If you run something like 1080ti or 2080ti + some extra card and you have to step down from PCIe 3.0 x16 to PCIe 3.0 x8 then you may actualy see some performance degradation in some scenarios as those cards may need more bandwidth in some situations than what x8 PCIe 3.0 can provide so PCIe 4.0 completely solves this as you can use half of the lanes and still have more than enough bandwidth.

 

This also means that if you had to buy the HEDT platform just because you had too many PCIe devices and the consumer platform could not handle it because it usualy had way too few lanes, now you can buy the consumer platform and likely be fine because PCI 4.0 has double the bandwidth.

[porina]

5 minutes ago, WereCat said:

Its a big deal even if we dont have PCIe 4.0 devices because you can still take the advantage of having twice the amount of bandwidth.

No argument about that on 500 chipset, but my comment was in reference to getting this on 400 platforms. Very few will actually make use of 4.0 in the short term. I mean, maybe Navi will launch at a similar time and support it in a more mainstream product, but it really isn't a "need". I will look forward to e.g. Hardware Unboxed who will probably test this when it comes out.

[mariushm]

One good thing about pci-e 4.0 is that it raises the bandwidth to 2 GB per lane. So it makes it possible to use pci-e x1 and x4 slots for more things, like for example a pci-e x1 slot for a 4K raw capture card (~1.5 GB/s of raw bandwidth for 4K 60fps RGB)

 

Would be nice to see adapter cards that take 8 pci-e lanes and split them into 8 m.2 connectors each with one 4.0 lane.... you plug 8 m.2 SSDs ... who needs fancy hba cards for a tiny NAS... just shove 8 2 TB SSDs into a pci-e x8 slot.

[WereCat]

15 minutes ago, porina said:

No argument about that on 500 chipset, but my comment was in reference to getting this on 400 platforms. Very few will actually make use of 4.0 in the short term. I mean, maybe Navi will launch at a similar time and support it in a more mainstream product, but it really isn't a "need". I will look forward to e.g. Hardware Unboxed who will probably test this when it comes out.

Yeah, on 400 series boards it will likely not be a big deal for most peple. But you can still get one of those PCIe to 4x NVME cards and pop it in if you want.

[leadeater]

48 minutes ago, Drak3 said:

If you're looking to blow $700+, the Radeon 7 uses the PCIe 4.0 bus.

Has everyone forgotten that AMD removed PCie 4.0 from Radeon VII and made it exclusive to the Instinct cards?

 

Quote

Past that, AMD will be employing some mild product segmentation here to avoid having the Radeon VII cannibalize the MI50 – the Radeon VII does not get PCIe 4.0 support

https://www.anandtech.com/show/13832/amd-radeon-vii-high-end-7nm-february-7th-for-699

[porina]

16 minutes ago, WereCat said:

Yeah, on 400 series boards it will likely not be a big deal for most peple. But you can still get one of those PCIe to 4x NVME cards and pop it in if you want.

It is not that you can't make use of it on 400 chipset, but the overwhelming majority would never do that. 

 

We'll see what happens when the dust settles after launch, but I think most that are performance inclined would most likely buy the new chipset at the same time. Maybe 400 boards will see discounts and pick up value hunters from that. 

[Drak3]

1 minute ago, leadeater said:

Has everyone forgotten that AMD removed PCie 4.0 from Radeon VII and made it exclusive to the Instinct cards?

 

https://www.anandtech.com/show/13832/amd-radeon-vii-high-end-7nm-february-7th-for-699

That's the first thing I've seen that says it doesn't use it.

[leadeater]

3 minutes ago, porina said:

It is not that you can't make use of it on 400 chipset, but the overwhelming majority would never do that. 

 

We'll see what happens when the dust settles after launch, but I think most that are performance inclined would most likely buy the new chipset at the same time. Maybe 400 boards will see discounts and pick up value hunters from that. 

I don't think there is going to much significant change on new motherboards until more products on the market are PCIe 4.0. The lane allocation pretty much has to take in to account almost nothing is 4.0 yet so you'd be designing something with a pretty fundamental flaw if you did so now.