[warning] Ryzen 5000G APUs, B550 and PCIe cards compatibility

[kriegalex]

Hi everyone,

 

TLDR: I just want to warn all homelab enthusiasts that APUs like the 5600G or 5700G, and apparently also the newer 8000G series can have issues with some PCIe cards, when paired with some motherboards. In my case, with a 5700G + B550 + E10M20-T1 (Synology), the card is not detected at all. I expect the same with the QM2 cards from QNAP with an integrated NIC.

 

When buying the Cezanne 5700G, and using a B550 motherboard, I saw that PCIe was going down from PCIe 4.0 to PCIe 3.0. What I didn't know is that the bifurcation options also go from

 

• x8/x8
• x8/x4/x4
• x4/x4/x4/x4

to

• x8/x8
• x8/x4/x4

This apparently breaks compatibility with cards like the E10M20-T1. Beware ! Maybe it is not linked at all, but the coincidence is too big.

 

It's sad, because this config makes for an excellent Ryzen SFF homelab machine with very fast NVMe storage, avoiding IPMI powered server MB by having an APU with a graphics output. It certainly helps with the budget, as server grade stuff is expensive.

 

For now, I'm using a 5900X without graphics, because luckily AM4 boards can boot without a graphics card installed.

[Blue4130]

7 minutes ago, kriegalex said:

Hi everyone,

 

TLDR: I just want to warn all homelab enthusiasts that APUs like the 5600G or 5700G, and apparently also the newer 8000G series should not be paired with some "NAS oriented" PCIe cards, such as the E10M20-T1 from Synology. The card is not detected. I think the same would be valid for QNAP or any other vendor that does cards with multiple PCIe entities on one single card (see details).

 

When buying the Cezanne 5700G, I saw that PCIe was going down from PCIe 4.0 to PCIe 3.0. What I didn't know is that the bifurcation options also go from

 

• x8/x8
• x8/x4/x4
• x4/x4/x4/x4

to

• x8/x8
• x8/x4/x4

This apparently breaks compatibility with cards like the E10M20-T1. Beware ! The most logical explanation is that the NIC, the 2x NVMe and the PCIe switch count as 4 devices and so require x4 bifurcation. I've reported the issue to Asrock. What is weird is that you are not supposed to setup IOMMU or bifurcation for the card to work on a normal Ryzen CPU.

 

It's sad, because this config makes for an excellent Ryzen SFF homelab machine with very fast NVMe storage (no bulk storage) for non media oriented containers, VMs, ... The APU allows you to free the PCIe slot for storage instead of graphics and allows to avoid buying expensive IPMI server boards and stay in the mini-ITX format.

• 5700G : 170$
• B550m-ITX : 120$
• 2x32GB DDR4-3200 : 130$
• Any SFF case + PSU : 150$ (probably less even)
• E10M20-T1 : 210$
• 3x2TB 980 Pro NVMe : 375$
• Total : ~1200$

An IPMI powered server MB + 2x32GB ECC RAM will already be around 500 to 700$ alone.

 

I know that people like to buy old used servers around here (and on r/homelab), but without a dedicated man cave, jet-powered Dell R700 & Cie are not a valid option

 

For now, I'm using a 5900X without graphics, because luckily AM4 boards can boot without a graphics card installed. So you install with a low power GPU, triple check that everything works, then you can remove the GPU and install the other PCIe device of your choice.

That's not a cpu issue, it is a motherboard issue. Any motherboard that doesn't support 4/4/4/4 bifurcation will have issue regardless of if it is Ryzen apu or intel.

[kriegalex]

43 minutes ago, Blue4130 said:

That's not a cpu issue, it is a motherboard issue. Any motherboard that doesn't support 4/4/4/4 bifurcation will have issue regardless of if it is Ryzen apu or intel.

I've updated the topic to not mislead people and made it shorter.

[Blue4130]

7 minutes ago, kriegalex said:

I've updated the topic to not mislead people

How much do you know about the synology card? I see that it is x8 and has one rj45 port and 2 nvme slots. How are they all split up? Does it have an actual PCIE switch chip?