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AMD: Pre-X570 boards will not support PCIe Gen 4
Yes, that's what he said. Actually, AMD's Robert Hallock said that on Reddit. earlier on some motherboard manufacturers showed PCIe Gen 4.0 support in series 400 BIOSes.
And that confirms it plain and simple. The new 500 series chipset will support PCIe express Gen 4.0 in combination with Ryzern 3000 processors. Anything below, simply not. Whether or not you'll find PCIe 4.0 a buying feature is also topic of debate, your GPU certainly will not need that bandwidth, and while PCIe Gen 4.0 based NVMe SSD(s) are fun, would you truly really need 5000 MB/sec in SSD performance, other than for bragging rights of course .
"Hallock: This is an error we are correcting. Pre-X570 boards will not support PCIe Gen 4. There's no guarantee that older motherboards can reliably run the more stringent signaling requirements of Gen4, and we simply cannot have a mix of "yes, no, maybe" in the market for all the older motherboards. The potential for confusion is too high. When final BIOSes are released for 3rd Gen Ryzen (AGESA 1000+), Gen4 will not be an option anymore. We wish we could've enabled this backwards, but the risk is too great."
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| PCIe Version | Line Code | Transfer Rate | x1 Bandwidth | x4 | x8 | x16 |
| 1.0 | 8b/10b | 2.5 GT/s | 250 MB/s | 1 GB/s | 2 GB/s | 4 GB/s |
| 2.0 | 8b/10b | 5 GT/s | 500 MB/s | 2 GB/s | 4 GB/s | 8 GB/s |
| 3.0 | 128b/130b | 8 GT/s | 984.6 MB/s | 3.938 GB/s | 7.877 GB/s | 15.754 GB/s |
| 4.0 | 128b/130b | 16 GT/s | 1.969 GB/s | 7.877 GB/s | 15.754 GB/s | 31.508 GB/s |
Fox2232
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Posts: 10067
Joined: 2012-07-20
#5676160 Posted on: 06/03/2019 08:56 AM
I doubt that signaling is an issue on such short distance. Linus did test PCIe 3.0 extension cable after extension cable and reached like 4 or six meters on PCIe 3.0 before he run into issue.
Sad, it would be nice to have PCIe 4.0 between 1st slot GPU and CPU on my quality x470 board. Nice, but unnecessary.
I doubt that signaling is an issue on such short distance. Linus did test PCIe 3.0 extension cable after extension cable and reached like 4 or six meters on PCIe 3.0 before he run into issue.
Sad, it would be nice to have PCIe 4.0 between 1st slot GPU and CPU on my quality x470 board. Nice, but unnecessary.
nevcairiel
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Posts: 672
Joined: 2015-05-19
#5676176 Posted on: 06/03/2019 09:50 AM
PCIe 4.0 has much more stringent requirements, though. On a board with multiple x16 slots, you'll already need re-drivers to enhance the signal to reach the bottom slots at full signaling strength.
Any test with PCIe 3.0 doesn't prove anything, since these things often interact exponentially. Also note that signaling in motherboard traces and in shielded cables of an extender is actually quite different, and shielded cables can go further without as much loss - but thats not an option for putting inside the PCB.
I doubt that signaling is an issue on such short distance. Linus did test PCIe 3.0 extension cable after extension cable and reached like 4 or six meters on PCIe 3.0 before he run into issue.
PCIe 4.0 has much more stringent requirements, though. On a board with multiple x16 slots, you'll already need re-drivers to enhance the signal to reach the bottom slots at full signaling strength.
Any test with PCIe 3.0 doesn't prove anything, since these things often interact exponentially. Also note that signaling in motherboard traces and in shielded cables of an extender is actually quite different, and shielded cables can go further without as much loss - but thats not an option for putting inside the PCB.
asturur
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Senior Member
Posts: 642
Joined: 2010-05-12
#5676177 Posted on: 06/03/2019 09:53 AM
Would have made x570 useless i believe. What does it do other than giving you pci express 4?
I belive someone will tweak the bios to try it out
Would have made x570 useless i believe. What does it do other than giving you pci express 4?
I belive someone will tweak the bios to try it out
Kaarme
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Joined: 2013-03-10
Senior Member
Posts: 1880
Joined: 2013-03-10
#5676179 Posted on: 06/03/2019 10:04 AM
I doubt that signaling is an issue on such short distance. Linus did test PCIe 3.0 extension cable after extension cable and reached like 4 or six meters on PCIe 3.0 before he run into issue.
Sad, it would be nice to have PCIe 4.0 between 1st slot GPU and CPU on my quality x470 board. Nice, but unnecessary.
I recall there were articles about the challenges for the mobo manufacturers back when it was first talked about how the next gen Ryzen will bring PCIe 4.0.
I don't see why they couldn't leave the option enabled for older mobos, turned off by default, of course. It's not like the old things would be marketed as PCIe 4.0 capable, after all. Their boxes/marketing material were made a long time ago, well before PCIe 4.0 was anywhere near actual use. If a mobo happened to work for some reason, swell, if not, that's to be expected. However, I'm sure the mobo manufacturers would rather sell new mobos. They must love the Intel scheme more in the long run. The AMD situation probably worked for them because there was much growth to be expected with Ryzen in the beginning, after all the dull years of Intel dominance and zero development. But if a Ryzen user isn't willing to buy a new mobo even after years of use and upgrading the CPU itself, it's a financial problem for the mobo makers.
I doubt that signaling is an issue on such short distance. Linus did test PCIe 3.0 extension cable after extension cable and reached like 4 or six meters on PCIe 3.0 before he run into issue.
Sad, it would be nice to have PCIe 4.0 between 1st slot GPU and CPU on my quality x470 board. Nice, but unnecessary.
I recall there were articles about the challenges for the mobo manufacturers back when it was first talked about how the next gen Ryzen will bring PCIe 4.0.
I don't see why they couldn't leave the option enabled for older mobos, turned off by default, of course. It's not like the old things would be marketed as PCIe 4.0 capable, after all. Their boxes/marketing material were made a long time ago, well before PCIe 4.0 was anywhere near actual use. If a mobo happened to work for some reason, swell, if not, that's to be expected. However, I'm sure the mobo manufacturers would rather sell new mobos. They must love the Intel scheme more in the long run. The AMD situation probably worked for them because there was much growth to be expected with Ryzen in the beginning, after all the dull years of Intel dominance and zero development. But if a Ryzen user isn't willing to buy a new mobo even after years of use and upgrading the CPU itself, it's a financial problem for the mobo makers.
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Tbh, I expected that. It's not big deal though.