Part PCIe 4.0 and riser cables beware.......

Obakemono

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Jan 20, 2019
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I had anticipated that there might be issues with the riser cable in my Phanteks Shift combined with my 5700XT and the X570-I mobo running at PCIe 4.0 speeds but the way it manifested was interesting. I had the 5700XT running on the cable with my X470 mobo with the current AMD drivers with no issues. Once I swapped out to the X570 mobo and reformatted everything the computer would load windows and do all the updates (PITA BTW) but then when installing AMD drivers that's when the fun began. During the install we all know that the screen will flicker and go blank while the drivers are loaded, but mine would shut the PC off. DEAD OFF. Power it back on and it would post, start to load windows and turn off again. So I had to get into the BIOS and set the PCIe to gen 3 and it all works fine now. I just wanted to give a head's up about this so if anyone running a riser cable (not rated for PCIe 4.0) you might have strange issues and will need to force the mobo to gen 3 to get it to work. I had called Phanteks about it to see if they had tested the riser at those speeds and they said no, so I told them I would give them feedback about my setup. Going to call them today and let them know the results.

O
 
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Nouvolo

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I have talked to a PCI-riser cable supplier, and from what I gathered we shouldn't expect PCIe 4.0 risers to come out anytime soon. Technical issues aside, there is one main business reason:

- Intel has not yet released their PCIe 4.0 motherboards yet.
PCIe riser manufacturers face risks of returns if Intel's version is not totally compatible with AMD's current version (if they claim it's PCIe 4.0 ready but end up not working with Intel). Nobody is certain whether just a BIOS update can fix things or some hardware tweaks is needed. So many PCIe riser suppliers would rather sit on the fence and wait for Intel's move.
 
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Obakemono

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Jan 20, 2019
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I have talked to a PCI-riser cable supplier, and from what I gathered we shouldn't expect PCIe 4.0 risers to come out anytime soon. Technical issues aside, there is one main business reason:

- Intel has not yet released their PCIe 4.0 motherboards yet.
PCIe riser manufacturers face risks of returns if Intel's version is not totally compatible with AMD's current version (if they claim it's PCIe 4.0 ready but end up not working with Intel). Nobody is certain whether just a BIOS update can fix things or some hardware tweaks is needed. So many PCIe riser suppliers would rather sit on the fence and wait for Intel's move.

Correct me if I am wrong but AMD would have not developed the specification for 4.0, only engineered their chipset to the PCIe standard, correct? Pardon my ignorance but does 4.0 have issues with riser cables? I know that trace run distance (or in case of risers, wire length) has an impact on the signal spec going to the video card. Intel would have to engineer and build to the same spec for PCIe 4.0 as well to be certified to sell their products, correct? There seems to be no issues between Intel and AMD with the PCIe 3.0 spec as far as I know.

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Nouvolo

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Correct me if I am wrong but AMD would have not developed the specification for 4.0, only engineered their chipset to the PCIe standard, correct?
You are correct, but nobody can guarantee until one can get hold of an Intel product to test, which doesn't exist now. It may work with Intel's but it may not be stable and require tweaks, and not be good enough as a final product.

Suppliers don't want to waste resources going back to tweak their design (originally that works with AMD, but then some issues with Intel).
 

dfrgu

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Mar 11, 2019
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You are correct, but nobody can guarantee until one can get hold of an Intel product to test, which doesn't exist now. It may work with Intel's but it may not be stable and require tweaks, and not be good enough as a final product.

Suppliers don't want to waste resources going back to tweak their design (originally that works with AMD, but then some issues with Intel).
But this is not always the case. Rome servers are coming and there ARE PCIe4 bases systems. Risers/NVMe cables are widely used in those servers. We may see those pcie accessories coming soon, but don't expect them to be cheap. There are some 100Gbe dual port NICs already based on PCIe Gen4.
 

VegetableStu

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Aug 18, 2016
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i feel like the rumor mills are quiet on intel's next gen systems after coffeelake desktop ._. (is it comet lake?) like when is the release forecast and the speculated chipset specs