Sunday, July 14th 2019

ASUS Begins Enabling Limited PCIe Gen 4.0 on AMD 400-series Chipset Motherboards

ASUS believes that PCI-Express gen 4.0 support on older socket AM4 motherboards based on the AMD 400-series chipset is technically possible, even if discouraged by AMD. The company's latest series of motherboard BIOS updates that expose PCIe Gen 4 toggle in the PCIe settings, does in fact enable PCIe gen 4.0 to all devices that are directly wired to the SoC. These would be the PCI-Express x16 slots meant for graphics, and one of the M.2 slots that has PCIe x4 wiring to the SoC. Below is a list of motherboards scored by Chinese tech publication MyDrivers, which details the extent of PCIe gen 4.0 support across a number of ASUS motherboards based on the X470 and B450 chipsets.

AMD apparently did not explicitly block PCIe gen 4.0 for older chipsets. It merely suggested to motherboard manufacturers not to enable it, since the newer AMD 500-series motherboards are built to new PCB specifications that ensure PCIe gen 4.0 signal-integrity and stability. ASUS wants to leave it to users to decide if they want gen 4.0. If their machines are unstable, they can choose to limit PCIe version to gen 3.0 in their BIOS settings. Among other things, AMD's specifications for 500-series chipset motherboards prescribe PCBs with more than 4 layers, for optimal PCIe and memory wiring. Many of the motherboards on ASUS' list, such as the TUF B450 Pro Gaming, use simple 4-layer PCBs.
To test that PCIe gen 4.0 is actually enabled, MyDrivers used a PCIe gen 4.0 SSD on the M.2 slot that's directly wired to the SoC, on a TUF B450M Pro Gaming. Crystal DiskMark sequential read speeds of the drive are consistent with the same drive tested on an X570 motherboard - with just over 5 GB/s reads. These speeds are impossible on gen 3.0 x4. In a separate article, MyDrivers reports that AMD isn't too happy with ASUS marketing PCIe gen 4.0 support on its 400-series motherboards, and is reportedly trying to block it in updates to the AGESA microcode. Our recommendation - if your updated ASUS 400-series motherboard is running PCIe gen 4.0, don't update its BIOS. Sources: MyDrivers (main story), MyDrivers (AMD's response)
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32 Comments on ASUS Begins Enabling Limited PCIe Gen 4.0 on AMD 400-series Chipset Motherboards

#1
Wavetrex
Mandatory X570 DoA comment ;)

I totally understand the need for progress, but PCIe 4.0 is so completely unnecessary right now that the very expensive boards officially supporting it are a bad joke.
Sounds like Nvidia's RTX.... great on paper, expensive, semi-useless in practice.

But well, those that want to be more "future proof" will pick one anyway.
Posted on Reply
#2
Crackong
High-end boards don't get it but the lower-end boards do, Why?
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#3
TheLostSwede
AMD has already stated this will not happen.
https://www.anandtech.com/show/14639/no-amd-still-isnt-enabling-pcie-4-on-300400-series-boards
Our plan is unchanged. For the reliability and consistency reasons cited at Computex, we still intend to disable PCIe Gen 4 for pre-X570 motherboards. That AGESA is being released to motherboard manufacturers soon.

Wavetrex, post: 4081022, member: 182738"
Mandatory X570 DoA comment ;)

I totally understand the need for progress, but PCIe 4.0 is so completely unnecessary right now that the very expensive boards officially supporting it are a bad joke.
Sounds like Nvidia's RTX.... great on paper, expensive, semi-useless in practice.

But well, those that want to be more "future proof" will pick one anyway.
Ah, but PCIe 4.0 will have a real use case soon enough, whereas RTX will never perform well on current cards...

Crackong, post: 4081023, member: 185495"
High-end boards don't get it but the lower-end boards do, Why?
It's all about the board design. If the x16 slot is too far from the CPU socket, it might not work. Same goes for the M.2 slot.
These boards weren't designed for PCIe 4.0, so you get signal quality issues if the PCB traces are too long.
This is why AMD decided against going ahead with this, even though they had intended to do so originally.
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#4
Berfs1
Not supported on crosshairs, but everything else. Ok.
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#5
Chaitanya
Wavetrex, post: 4081022, member: 182738"
Mandatory X570 DoA comment ;)

I totally understand the need for progress, but PCIe 4.0 is so completely unnecessary right now that the very expensive boards officially supporting it are a bad joke.
Sounds like Nvidia's RTX.... great on paper, expensive, semi-useless in practice.

But well, those that want to be more "future proof" will pick one anyway.
So I guess the NICs, SSDs, RAID cards, etc used for servers are going to be useless and waste of time since according to you PCI-E 4.0 is unnecessary.
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#6
Lightofhonor
Noticed it the other day on my board. Didn't know if it did anything, so left it alone.

Guessing the cheaper boards are getting it since they have fewer pcie lanes used so enabling pcie 4 doesn't affect too much, where crosshair may need to disable other ports which may prevent it from being useful depending on which ports would stop working.
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#7
Athlonite
I find it funny that the TUF B450 Plus Gaming gets atleast M.2_1 X4 PCIe 4.0 but then the same TUF X470 Plus Gaming doesn't they're practically the same mobo the only difference is the south bridge

TUF B450 Plus Gaming


VS

TUF X470 Plus Gaming

Posted on Reply
#8
Lightofhonor
Athlonite, post: 4081043, member: 80893"
I find it funny that the TUF B450 Plus Gaming gets atleast M.2_1 X4 PCIe 4.0 but then the same TUF X470 Plus Gaming doesn't they're practically the same mobo the only difference is the south bridge

TUF B450 Plus Gaming


VS

TUF X470 Plus Gaming


Possible they only want it on the B boards since they want people to buy the X570 boards they sell. There aren't B550 boards yet.
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#9
ObiFrost
Chaitanya, post: 4081034, member: 93474"
So I guess the NICs, SSDs, RAID cards, etc used for servers are going to be useless and waste of time since according to you PCI-E 4.0 is unnecessary.
Are we talking about regular market or enterprise market? For regular market it is clearly DOA, vast majority can't properly exploit PCIe 3.0 due to only gaming use and mildly workstation. Enterprise is a totally unrelated branch, those who work there know their requirements and nobody mentioned it's a wasted potential for them. On top of that, anyone with sensible mind and good nerves know that RAIDs are hazard, forcing the user constantly backup files. I often shake my head why average consumers enable RAID for gaming and then cry why their SSDs lifespan is rapidly decreasing...
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#10
T1beriu
Fake and old news. Not happening.
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#11
Metroid
Berfs1, post: 4081030, member: 163173"
Not supported on crosshairs, but everything else. Ok.
So much fun hehe, i guess people did not understand what you said hehe, anyway that is very funny, high end motherboards never support it because asus know people who buy those high end motherboards have money to buy more high end motherboards. So this is kind normal, asus never give support on high end motherboards, low end motherboard supports it.

T1beriu, post: 4081063, member: 164497"
Fake and old news. Not happening.
It already happened. Bios is out and about.
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#12
goodeedidid
Wavetrex, post: 4081022, member: 182738"
Mandatory X570 DoA comment ;)

I totally understand the need for progress, but PCIe 4.0 is so completely unnecessary right now that the very expensive boards officially supporting it are a bad joke.
Sounds like Nvidia's RTX.... great on paper, expensive, semi-useless in practice.

But well, those that want to be more "future proof" will pick one anyway.
You suggest they release the tech after it is necessary?
Posted on Reply
#13
Emanulele
Metroid, post: 4081064, member: 178915"
So much fun hehe, i guess people did not understand what you said hehe, anyway that is very funny, high end motherboards never support it because asus know people who buy those high end motherboards have money to buy more high end motherboards. So this is kind normal, asus never give support on high end motherboards, low end motherboard supports it.



It already happened. Bios is out and about.
They can't support it because the motherboard uses a bunch of PLX PCI-E switches that do not support PCI-E 4.0, the switches are actually good as they add some flexibility on the use of the lanes. In fact on the Crosshair VII you have 4.0 on M2_1 as the lanes are directly from the CPU there.
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#14
TheLostSwede
Lightofhonor, post: 4081042, member: 63511"
Noticed it the other day on my board. Didn't know if it did anything, so left it alone.

Guessing the cheaper boards are getting it since they have fewer pcie lanes used so enabling pcie 4 doesn't affect too much, where crosshair may need to disable other ports which may prevent it from being useful depending on which ports would stop working.
I think you've misunderstood how it works. Only the first x16 slot and the M.2 connector wired to the CPU could potentially support PCIe 4.0, the rest of the slots/connectors, can not.

ObiFrost, post: 4081057, member: 186018"
Are we talking about regular market or enterprise market? For regular market it is clearly DOA, vast majority can't properly exploit PCIe 3.0 due to only gaming use and mildly workstation. Enterprise is a totally unrelated branch, those who work there know their requirements and nobody mentioned it's a wasted potential for them. On top of that, anyone with sensible mind and good nerves know that RAIDs are hazard, forcing the user constantly backup files. I often shake my head why average consumers enable RAID for gaming and then cry why their SSDs lifespan is rapidly decreasing...
Say what? My M.2 NVMe SSD can use it, my 10Gbps Ethernet card can use it, the fact that a graphics card can't fully utilise the bandwidth in a x16 slot, doesn't mean other devices can't...
Anyone using Thunderbolt 3 is using upp four lanes of PCIe 3.0.
Just because You don't use it, doesn't mean there aren't use cases for it.

T1beriu, post: 4081063, member: 164497"
Fake and old news. Not happening.
Fake, no, as Asus has clearly advertised it in China by the looks of the presentation posted. However, AMD is set to properly block it soon enough, which might end in tears for some.
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#15
RH92
So somehow lower end boards meet the requirements for PCIe 4.0 but the high end ones and ITX don't ? This is total nonsense !
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#16
JB_Gamer
I have a r5-3600 plus a ASUS ROG STRIX X470-F GAMING motherboard, updated to UEFI/BIOS 5007, but I can't find any PCIe toggle - to 4.0. And the latest GPU-Z reports just PCIe 3.0 just as the new bandwidth test i 3DMark does, so what...? Anyone?
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#17
Mephis
vprem, post: 4081070, member: 176373"
Lke it or not, when Your Friend is Your Enemy's Enemy, "Asus" had to be Congratulated for Acting To "Protect Its Investent". You shorely knowz how much "Time & Money" went to "Designing & Making Motherboards" and no Joker, be said entity "Red-Coloured" [or even "Blue-Coloured], be "Gallivanting On Some, More Money Than Sense" Advertisement-Driven-Crusade, or not. More so when "[almost] NOBODY seems to-be "Buying Zhose Velly-Expensive Jokes", sump'fing gottas be dunn !

"Auntie-Red" might be all a-flustered over "Zist, Zat, und Zer-Other", but let her, "Fume All She Likes". More so when "Investment of Time & Money, Rulez, AOK" ! But becareful when, "A Cat's-Claws are UnFurled". There is more to Unfurling Dem-Claws Than Meets-The-Eye !!

Well done, "Asus". When Strange-Bedfellows are "A-Bedding" who, knowz what will be "Off-Springing" !! Especially when, "More Money Than Sense", aka "Industry", is [seemingly] not-tempted. Yet! But when "Easy-Come" aims to-promote "Easy-Go", Dem-Smelly-Lot will soon be rushing out, "To-Spend,Spend,Spend". More so when "Deep-Pockets" are lined with "Itchy-Fingars", aka, "More Money Than Sense".
Dude, lay off the drugs or just take a half dose next time.
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#18
TristanX
Intel paid Asus to enable PCIE 4 support. Reason is decrease revenues from x570 sales
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#19
BorgOvermind
Crackong, post: 4081023, member: 185495"
High-end boards don't get it but the lower-end boards do, Why?
Because it's a lower standard.
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#20
Death Star
It's not as simple as "flicking a switch" to enable compatibility with a spec which increases data transfer rate by a factor of 2.

This isn't a simple DC wiring problem, it's a time-varying signal which needs to propagate along many transmission lines in the extremely crowded environment of a motherboard PCB. By flipping the switch to double the throughput, you can easily push the circuit outside of it's spec in a number of ways .
- Signal to noise may be violated
- Additional cross talk
- Increased clock jitter
- Disruption of power delivery integrity.

Doubling any switching frequency from a circuit's design spec can break a circuit's capacitive and inductive tuning and completely change the shape of the signal. Anything carrying a current which oscillates in time has the potential to radiate (i.e. becomes an antenna), anything which radiates interacts with and affects its surrounding environment, anything which radiates will be affected by its surrounding environment.

TL : DR - It's not as simple as flipping a switch because electromagnetics are complicated. But also, businesses will be businesses, and only Asus's design engineers would know the exact spec range of their circuitry.

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#21
Berfs1
TheLostSwede, post: 4081098, member: 3382"
I think you've misunderstood how it works. Only the first x16 slot and the M.2 connector wired to the CPU could potentially support PCIe 4.0, the rest of the slots/connectors, can not.



Say what? My M.2 NVMe SSD can use it, my 10Gbps Ethernet card can use it, the fact that a graphics card can't fully utilise the bandwidth in a x16 slot, doesn't mean other devices can't...
Anyone using Thunderbolt 3 is using upp four lanes of PCIe 3.0.
Just because You don't use it, doesn't mean there aren't use cases for it.


Fake, no, as Asus has clearly advertised it in China by the looks of the presentation posted. However, AMD is set to properly block it soon enough, which might end in tears for some.
While yes you would pay more for X570 if you am afford the Crosshair price, i always thought the Crosshair, Maximus, Dominus, Rampage, Crossblade, and Zenith lineups were the strongest, and therefore should have support for the features if they are physically capable of those features.

EDIT: I replied to the wrong post because there’s so many similar posts. Sorry
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#22
Athlonite
JB_Gamer, post: 4081117, member: 173137"
I have a r5-3600 plus a ASUS ROG STRIX X470-F GAMING motherboard, updated to UEFI/BIOS 5007, but I can't find any PCIe toggle - to 4.0. And the latest GPU-Z reports just PCIe 3.0 just as the new bandwidth test i 3DMark does, so what...? Anyone?
Because your GPU only supports PCIe 3.0 if you were to stick an PCIe 4.0 cappable GPU in it's place then it would probably say PCIe 4.0
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#23
Mistral
Seriously, what's the worst that could happen...?
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#25
RH92
Athlonite, post: 4081270, member: 80893"
Because your GPU only supports PCIe 3.0 if you were to stick an PCIe 4.0 cappable GPU in it's place then it would probably say PCIe 4.0
That's not how it works you can put a PCIe 2.0 device on a PCIe 3.0 port it wont stop you from enabling PCIe 3.0 on your mobo , same goes here .
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