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Associate
- Joined
- 27 Jan 2019
- Posts
- 57
good question. I was wondering this myself. I just hope Asus will allow PCIE 4.0 with a bios update on my B450-I, Its perfect size for my build. These new Cooling systems on the new Mobos are insanely big and will make me have to rethink where my pump is.
Educated guess but a cable is just wiring. As long as they don't fiddle with the connections, which they wont for backwards compatability, cable should not matter. Are riser cables rated as pcie 3 currently?
Yes, and I remember there being issues with those to start with.
Soldato
I'm sure I've read that PCI-E 4.0 bandwidth is dependant on the distance the signal has to travel, if you start adding in extensions then you might be fine for PCI-E 3.0 but possibly not for 4.0...
Soldato
Given all the talk about signal integrity and interference issues that had to be tackled to make PCIe 4.0 work on x570 I doubt that a PCIe riser cable would support it. However if you are using the PCIe slot for a GPU then the extra bandwidth of 4.0 won't benefit you anyway.
Cables are likely not as problematic as PCB traces, but there are additional connections too. As a pure guess I think you'd be looking at new more expensive riser cables with higher quality and/or retimers built in to maintain the 4.0 speeds.... debatable whether it matters given the bandwidth requirements of current GPUs though. I'm sure someone will do some tests with PCIe 4.0 boards and riser cables to see if there is any frame rate impact.
edit - interesting quote
https://www.eetasia.com/news/article/18061502-pcie-45-higher-bandwidth-but-at-what-cost
edit - interesting quote
https://www.eetasia.com/news/article/18061502-pcie-45-higher-bandwidth-but-at-what-cost
That may be true for this generation of GPUs but what about the next one? And the one after that?
Soldato
I've not seen anyone say pcie 3.0 16x is fully utilised yet with todays GPU.
It isn't, but 8x is.
Soldato
So it doesnt matter about future generations PCIE4 is still not needed. Especially considering the length of time that the above has took to become utilised by GPU's
Soldato
I predict that by that point the AM4 platform will be outdated and it won't matter that you don't have 4.0 bandwidth.
But it will that you've exceeded 3.0 bandwidth. Two GPUs - or one GPU and a SSD array - will already soak a 16x 3.0 bus.
Soldato
You won't exceed 3.0 bandwidth either. I don't think there is a situation where you'd have to use a riser cable in a dual GPU setup nor for an SSD array.
Associate
Soldato
if you have the dan 4 then that will ship with gen 3 riser cable, my dan a4 v4.1 shipped with a gen 4 riser cable, also nzxt's new h1 case comes with a gen 3 but has plans to offer a upgrade to owners of the first run cases, it was said to be working on a new revision of the h1 that includes a gen 4 riser standard.
when they were designing the case gen 4 wasn't a thing until it came to market, so instead of delaying the case launch they decided to ship with gen 3 risers instead.
tbh gen 4 pci-e is in its infancy and no real world use cases so any real benefit to using it, gen 3 will work perfectly fine as is
Caporegime
I think the 5700s have/had problems when used with riser cables.
Soldato
you can get around that by setting gen 3 pci-e support via the bios, that way any card will work