Question New AMD Ryzen 7000 and older PCI-E Cards

braxus

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Jan 1, 2018
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Im debating at some point to move up the the AM5 CPU. I'll probably stick with Gigabyte for the motherboard. My question is this. Is it true you have to completely replace almost all the electrical components of the system to move up to AM5? Reason I ask is I have 3 or 4 PCI-E 1.0 cards I use in my system (not including the video card). I take it I won't be able to use those older cards in the new board? I have some cards for video capture, 1394, and one for an older IDE device I still use. I don't believe the market will make new PCI-E 5.0 cards to replace what I have now. So am I out of luck, or will the AM5 setup allow the use of 1.0 cards? I heard this may be the case, which kept me from upgrading to AM5 in the first place. I dont mind replacing my GPU or memory, but the add in cards is the problem.

Reason is I like to build a system capable of 8K video editting. Im running the 5900X right now and my system struggles with 4K video without upgrading the memory or using the Pro version of software. My 4K files are 200mb compression.

Also is older SATA supported under AM5? I also have a Blu Ray burner which I still use, plus some SATA mechanical hard drives.

Or is this just too soon to know the specifics of AM5 compatability?
 
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Normally yes, but I was told by my family member the AM5 will only go back to 4.0. That was my concern.
Ask them for proof. If they only provide a vague response or some reddit post that doesn't also provide proof, then it's not a thing.

Besides, in addition to backwards compatibility, PCIe speeds are often slowed down on video cards when they're idling or under low loads because there's no reason to have them get data that fast and keeping PCIe speeds fast increases power consumption.
 

braxus

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Jan 1, 2018
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So with the Ryzen 7000 series coming soon for release, my original question seems to reappear. I was looking for info on the 7900X and I saw this in one of the comments for that CPU:

"The US price for AMD Ryzen 9 7900X is around $550. Ryzen 9 7900X will only support DDR5 RAM and PCIe Gen5. "

When they say it will only support PCIe Gen 5, does this mean its not backwards compatible with older PCIe cards like Gen 4 and earlier?
 
So with the Ryzen 7000 series coming soon for release, my original question seems to reappear. I was looking for info on the 7900X and I saw this in one of the comments for that CPU:

"The US price for AMD Ryzen 9 7900X is around $550. Ryzen 9 7900X will only support DDR5 RAM and PCIe Gen5. "

When they say it will only support PCIe Gen 5, does this mean its not backwards compatible with older PCIe cards like Gen 4 and earlier?

It seems poorly worded to to me: I think it only means DDR5 RAM only, which is something we do know.

AMD would have a debacle releasing a platform (CPU/chipset/motherboard) that can't support PCIe gen 4 as well as PCIe gen 3 GPU's into a market that's not only flush with them but has ZERO PCIe gen 5 GPU's (in so far as I know).That would be a non-starter to say the least.
 
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Im debating at some point to move up the the AM5 CPU. I'll probably stick with Gigabyte for the motherboard. My question is this. Is it true you have to completely replace almost all the electrical components of the system to move up to AM5? Reason I ask is I have 3 or 4 PCI-E 1.0 cards I use in my system (not including the video card). I take it I won't be able to use those older cards in the new board? I have some cards for video capture, 1394, and one for an older IDE device I still use. I don't believe the market will make new PCI-E 5.0 cards to replace what I have now. So am I out of luck, or will the AM5 setup allow the use of 1.0 cards? I heard this may be the case, which kept me from upgrading to AM5 in the first place. I dont mind replacing my GPU or memory, but the add in cards is the problem.

Reason is I like to build a system capable of 8K video editting. Im running the 5900X right now and my system struggles with 4K video without upgrading the memory or using the Pro version of software. My 4K files are 200mb compression.

Also is older SATA supported under AM5? I also have a Blu Ray burner which I still use, plus some SATA mechanical hard drives.

Or is this just too soon to know the specifics of AM5 compatability?
Now...i'm not so sure. Maybe there's something to this for the X670E chipset.....check this AnandTech page, chipset comparison chart:

https://www.anandtech.com/show/1755...hipset-for-ryzen-7000-pcie-5-0-for-mainstream

According to that, PCIe gen 5 is MANDATORY on X670E boards. That really seems crazy to me since only X670E boards are going to be available at launch of Ryzen 7000 and to my knowledge there are no PCIe gen 5 GPU's currently available. This may be the boringest launch ever as everybody will be using the weak and "very basic" iGPU until some decent discrete Gen 5 capable GPU's come on market.

But wait....it's not well explained in the article text but this chart may be referring to requirements that AMD makes on motherboard mfr's. What it is saying is AMD REQUIRES a motherboard be PCIe gen 5 CAPABLE if they use the X670E chipset....OPTIONAL for the X670 and HIGHLY SUGGESTED for the B650E. Not said is whether it is....or is not...just as backwards compatible as earlier generations.

AMD imposing requirements like this makes sense as the PWB data path layout is far more critical for gen 5 so the cost is much higher....usually more PWB layers required. Some mfr's may try to cheap out on the PWB which would not play well with AMD's product stack.

So...confusion. But we'll be finding out more as we get some reviews coming out. That's why it's never a good idea to buy brand-new tech at launch. Give the tech reviewers a chance to kick the tires a little before you take the leap.
 
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Besides, in addition to backwards compatibility, PCIe speeds are often slowed down on video cards when they're idling or under low loads because there's no reason to have them get data that fast and keeping PCIe speeds fast increases power consumption.
Have you seen this in desktops? I've only seen this behavior in laptops, 2-in-1s, and the like.

For the OP - New PCIe generations will ALWAYS be backwards compatible with older generations. It's part of the PCIe standard.
1st, 2nd, 3rd, and 4th gem PCIe devices will work perfectly fine in 5th gen PCIe computers as long as the interface is the same. They may work at slower speeds, but they will work.
 
Now...i'm not so sure. Maybe there's something to this for the X670E chipset.....check this AnandTech page, chipset comparison chart:

https://www.anandtech.com/show/1755...hipset-for-ryzen-7000-pcie-5-0-for-mainstream

According to that, PCIe gen 5 is MANDATORY on X670E boards. That really seems crazy to me since only X670E boards are going to be available at launch of Ryzen 7000 and to my knowledge there are no PCIe gen 5 GPU's currently available. This may be the boringest launch ever as everybody will be using the weak and "very basic" iGPU until some decent discrete Gen 5 capable GPU's come on market.

But wait....it's not well explained in the article text but this chart may be referring to requirements that AMD makes on motherboard mfr's. What it is saying is AMD REQUIRES a motherboard be PCIe gen 5 CAPABLE if they use the X670E chipset....OPTIONAL for the X670 and HIGHLY SUGGESTED for the B650E. Not said is whether it is....or is not...just as backwards compatible as earlier generations.

AMD imposing requirements like this makes sense as the PWB data path layout is far more critical for gen 5 so the cost is much higher....usually more PWB layers required. Some mfr's may try to cheap out on the PWB which would not play well with AMD's product stack.

So...confusion. But we'll be finding out more as we get some reviews coming out. That's why it's never a good idea to buy brand-new tech at launch. Give the tech reviewers a chance to kick the tires a little before you take the leap.
Think of the X670E, X670, B650E, and B650 as minimum requirement badges.

The X670E is required to have PCIe 5 NVMe and GPU slots. The others have different requirements for how many GPU/RAM/NVMe slots are present and how many have to be PCIe 5.
But the ones that have PCIe 5 still use the PCIe5 standard, which includes backwards compatibility with all previous generations of PCIe devices.

DDR5 is the only memory type supported though. There will be no DDR4 with Ryzen 7000 (and up).
 
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But the ones that have PCIe 5 still use the PCIe5 standard, which includes backwards compatibility with all previous generations of PCIe devices.
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I like to think so too...but it IS an extensive standard update (DOUBLING bandwidth again) that's also come with new PCIe power connector design requirements. I've not seen much on it beyond the Anandtech article saying PCIe gen 5 is MANDATORY (for X670E). Not a problem to wait until the reviewers have had their chance to poke at the new tech, IMO.

That is, unless someone's actually reviewed the revised PCIe spec's to confirm full backward compatibility is retained, of course.
 
That is, unless someone's actually reviewed the revised PCIe spec's to confirm full backward compatibility is retained, of course.
It's literally part of the PCI-SIG standard.

https://en.wikipedia.org/wiki/PCI_Express


The only exceptions with PCIe backwards compatibility (in the 1.0-2.1 stages) was due to the governing body still trying to figure out proper power delivery.
So, unless you have a 19 year old, PCIe1.0 GPU that you want to try and use in the PCIe 5 slot, you're good. Also note that this isn't even a given. It was only with some PCIe cards that you'd have an issue.

Anything less than this doesn't meet the PCIe 5.0 spec.
 
Have you seen this in desktops? I've only seen this behavior in laptops, 2-in-1s, and the like.
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