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  #11  
Old 12-07-19, 04:17 PM
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AlienALX AlienALX is offline
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The reason things are going down like this is literally down to how the board etc is built. It's luck mostly. However, AMD could not guarantee PCIE 4.0 would work on every existing board.

It's kinda like that time you could patch your PCIE 2.0 rig to 3.0 if you had at least an Ivy CPU. In fact, you could even enable PCIE 3.0 on certain Sandy CPUs (3970x was one).

Still there's no need to complain if you buy a 400 series board. They are still the same price they were before 570x came out. And, probably the better to live with too.

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  #12  
Old 12-07-19, 05:14 PM
Bartacus Bartacus is offline
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Quote:
Originally Posted by AlienALX View Post
The reason things are going down like this is literally down to how the board etc is built. It's luck mostly. However, AMD could not guarantee PCIE 4.0 would work on every existing board.

It's kinda like that time you could patch your PCIE 2.0 rig to 3.0 if you had at least an Ivy CPU. In fact, you could even enable PCIE 3.0 on certain Sandy CPUs (3970x was one).

Still there's no need to complain if you buy a 400 series board. They are still the same price they were before 570x came out. And, probably the better to live with too.
Back in the x79 days, if you had the right board, you had PCIE 3.0 on every socket 2011 CPU. I had it on my 3820k. But you needed a high end board (mine was the Asus Rampage IV Gene). That board was advertised as "PCIE 3.0 ready" at the time.
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  #13  
Old 12-07-19, 05:17 PM
Gothmoth Gothmoth is offline
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Originally Posted by Avet View Post
I don't know why people are complaining. AMD gave you an option when first Ryzen launched to use any board with any CPU. Please don't put 12 core CPU on the cheapest B350 motherboard.
i don´t see complains here regarding that.


personally i just wonder that the cheap TUF boards get support for PCI 4.0 on the first PCIE slot and the way more expensive crosshair not....
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  #14  
Old 12-07-19, 05:22 PM
NeverBackDown NeverBackDown is offline
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Originally Posted by Gothmoth View Post
i don´t see complains here regarding that.


personally i just wonder that the cheap TUF boards get support for PCI 4.0 on the first PCIE slot and the way more expensive crosshair not....
signal integrity...
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  #15  
Old 12-07-19, 05:34 PM
Gothmoth Gothmoth is offline
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signal integrity...

still suprising that signal integrity is better on cheaper boards. not?


you could think a bit of the money goes into better PCB and signal integrity for OC boards like the cosshair. not just water pump connections, fan headers, rgb lighting and stuff.
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  #16  
Old 12-07-19, 08:03 PM
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AlienALX AlienALX is offline
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Quote:
Originally Posted by Bartacus View Post
Back in the x79 days, if you had the right board, you had PCIE 3.0 on every socket 2011 CPU. I had it on my 3820k. But you needed a high end board (mine was the Asus Rampage IV Gene). That board was advertised as "PCIE 3.0 ready" at the time.
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  #17  
Old 12-07-19, 11:00 PM
robbiec robbiec is offline
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Hehe I almost called it right on the day of the release, I queried if AMD / Asus had cooked up some magic to allow PCIE to run from the CPU. Now all I need is for Samsung to release some NVMe hitting 6GB/s
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  #18  
Old 14-07-19, 05:52 PM
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hmmblah hmmblah is offline
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Cleaned up the thread a bit. No need for name calling or trying to bypass the swear filters.
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  #19  
Old 15-07-19, 12:29 AM
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Avet Avet is offline
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Originally Posted by Gothmoth View Post
still suprising that signal integrity is better on cheaper boards. not?


you could think a bit of the money goes into better PCB and signal integrity for OC boards like the cosshair. not just water pump connections, fan headers, rgb lighting and stuff.
I have already explained it in the previous post.

Quote:
Originally Posted by Avet View Post
The prominent issue is signal integrity. You can see that m.2 slots are just below the CPU. They are very close and, as stated in the article, those are primary m.2 slots with CPU lanes. Also with PCIe x16 slot, only boards that don't support SLI/CF have some support for PCIe 4.0. Again, they have only one PCIe slot that is connected to CPU. Boards that have lane dividers (a bunch of those square chips that you see between PCIe slots) and support for SLI/CF, in this case, higher-end boards, don't support PCIe 4.0. The second slot is very far from the CPU, and lane dividers don't support PCIe 4.0. That is why you need better-built PCBs and different components. ITX boards have extremely densely packed PCBs, with traces going all around everywhere so I assume it is too noisy to keep adequate signal integrity for PCIe 4.0, hence no support.

PCH has nothing to do with support on x470 boards because support is related only to CPU lanes.

If you know very basic stuff about PCIe lanes, and how stuff is organized on the motherboard it is very logical and makes sense.

If there are any engineers there please correct me if I am wrong.
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  #20  
Old 15-07-19, 02:32 AM
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Kleptobot Kleptobot is offline
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Just to clarify a couple of points regarding signal integrity as i think this is where the discussion is breaking down

Because PCIe is a serial bus there is a lot of very high frequency switching going on
High frequency signals can create issues regarding leaking (cross coupling) into nearby traces
What is ok for one switching frequency may not be ok for another
If a board was tested to work acceptably with PCIe3.0 there is no guarantee that it will work well for PCIe4.0
The distance between traces, the angle at which traces cross other traces, how many layer changes the traces go through the proximity to certain components all affect a trace's ability to carry a signal and what frequency those signals can be.

The ability to do good circuit board layout is almost black magic as it is. Sometimes the person doing the layout doesn't even know what the individual traces are doing. They are just given a list of rules that must be followed.

So while it may seem arbitrary what boards do and don't support PCIe4.0 it's most likely down to some design decisions were made that were completely fine, or possibly better, for PCIe3.0 that are not fine for PCIe4.0.

These decisions are not as clear cut as lower quality parts or cheaper copper, but highly nuanced.
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