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RastaMasikDjon
Journeyman III

How many PCI-E 4.0 lanes does the Ryzen 9 3900X support?

I use an NVMe PCI-E 4.0 drive, RX6600 paired with a Ryzen 9 3900X. RAM frequency 3600MHz 32Gb. AMD SAM technology enabled. Works without problems for 6 months. I want a video card from Nvidia with PCI-E 4.0 x16, so as not to overload the lines of this harmful ZEN2 processor, I need to know the exact number of lines it supports.

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10 Replies
johnnyenglish
Grandmaster

You should have 16x for PCIe slots + 4x for NVMe + 4x for chipset

But each board has its own way of assignment.

Example, if you have 3 NVMe slots and two of them are fed from CPU, then it will share 2x+2x between them.

In your case its all good, the card will have the full 16x as long as you don't have more expansion cards.

The Englishman
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board Asus TUF Gaming B550M-Plus
Look, there is only one chipset, it’s difficult for me to understand (1 x M.2_1 socket 3, with M Key) - this means that processor lines are used, let’s assume that the Ryzen 9 3900x has 20 of these lines and not 12, then I can upgrade. Where is the truth?

Expansion Slots
AMD Ryzen™ 5000 Series/ 3000 Series Desktop Processors
1 x PCIe 4.0 x16 (x16 mode)
AMD Ryzen™ 4000 G-Series Desktop Processors
1 x PCIe 3.0 x16 (x16 mode)
AMD B550 Chipset
1 x PCIe 3.0 x16 (x4 mode)
1 x PCIe 3.0 x1

Storage

Total supports 2 x M.2 slot(s) and 4 x SATA 6Gb/s ports
AMD Ryzen™ 5000 Series/ 3000 Series Desktop Processors :
1 x M.2_1 socket 3, with M Key, Type 2242/2260/2280 (PCIE 4.0 x4 and SATA modes) storage devices support
AMD Ryzen™ 4000 G-Series Desktop Processors :
1 x M.2_1 socket 3, with M Key, Type 2242/2260/2280 (PCIE 3.0 x4 and SATA modes) storage devices support
AMD B550 Chipset :
1 x M.2_2 socket 3, with M Key, Type 2242/2260/2280/22110(PCIE 3.0 x4 and SATA modes) storage devices support
4 x SATA 6Gb/s port(s),

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Its not an assumption, it has 20+4 lanes. The X version of the AM4 Zen lineup has this configuration, even my 2700X had.

The list you posted is what is supported not what is used.

If you exchange the RX card for a new one then the full 16 lanes are available. If you use both cards, doesn't matter what the slot supports, the lanes will be shared. 8x plus 8x.

The Englishman
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cool, I understand you, thank you. I do home assemblies, I assembled this system for myself. I was confused, I decided to test myself. thanks again.

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RastaMasikDjon
Journeyman III

I check the specifications of the 3000 line processors and came to the conclusion that almost all of them support 16 lanes, except for the Ryzen 3 3200G it has 8 PCI-E 3.0 lanes, and the Ryzen 9 3950X has 20 PCI-E 4.0 lanes. If I'm wrong, correct me and in what program can I watch this?

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Can you point me where you did checked this information?

Anyway, just download any hardware info application (like GPUz) and it will tell you how many lanes the GPU is using or the NVMe.

I already checked on a 1700X, 2700X and a 3700X and 16x lanes were assigned for the GPU and 4x for storage.

The 3900X should be no different.

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The Englishman
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Снимок.PNG

 

This indicates the support of the motherboard and what is being used. There are no additional lines in the specification on the official website. I don’t want the chip to fail as it happens, and I will definitely write if this happens.

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The image is right, I completely forgot that the RX6600 only takes 8x lanes.

The chip won't fail if there aren't additional lanes. 

The Englishman
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RastaMasikDjon
Journeyman III

I understand that it won't burn out; it's just that the PCI-E lines may be limited. In my case, I won't see a drop in performance. However, considering the reliability of the ZEN2 microarchitecture controller, anything can happen. I would like to adhere to the specification. There is no information about the lines anywhere. Probably, this architecture is as experimental as possible, and all chips are not the same in every sense.

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I'm sorry but I highly doubt that a damage may occur from lane assignment.

There are so many people out there using 2 or 3 NVMe in their systems and not a single report came out "viral". Not to mention creators and streamers who use dual GPU.

The Englishman
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