I would like some clarification on B550 capabilities

[AquaVixen]

So today is the day. B550 is launched. We finally have the actual specifications and more importantly: Block diagram for B550. So I'm looking over the block diagram and several things are confusing. I'll post a screenshot of the block diagram in question and then below that my questions and concerns. Also I want to comment on my planned configuration for a future build and ask if someone can tell me if it will all work. And if it won't work, what sacrifices I would have to make.

 

First the block diagram here:

 

Concerns and where I'm confused:

1.) If it's only providing PCIE-3.0-x4 down-link to the chipset, then how can the chipset provide a PCIE-3.0-x8 connection if it's only getting a PCIE-3.0-x4 connection to the CPU?

3.) If I use the full speed of the USB 3.2 Gen2 10 Gbps ports on a B550 board, does that mean I will completely saturate / use up the entire PCIE-3.0-x4 connection to the chipset and effectively have to disable all other chipset based functions?

 

Now the build I had planned described here:

I wanted to build a file server + VM server + host multiple game servers + small traffic web servers / etc. based on a Mini-ITX B550 board. I've worked out how to connect 11 physical hard drives in a small computer case and I want to run them on a hardware accelerated raid card. I know software linux raid is an option but I do not want to go that route. Please do not let this thread dissolve in to software vs hardware raid. That's an entirely other discussion and off topic. I want hardware raid and I will use hardware raid and that's the end of it. I do not want to discuss it.

 

So this was my plan:

Mini-ITX B550 motherboard.

PCIE-3.0-x8 hardware raid card (Storage)

1 x PCIE-4.0-4x NVME drive (BOOT/OS/VM)

If possible, add second PCIE-4.0-x4 second NVME drive on bottom port and RAID-0 both NVME drives together.

I had hoped for using USB-C 10-GiG-E adapter. Motherboards have USB 3.2 Gen2 10 Gbps onboard. If I can find an adapter then theoretically the boards should have enough bandwidth to handle that at full speed.

 

So the question is: Can I do this all with B550? Raid card + NVME drive @ full speed + USB 10-GiG-E @ full speed (primary concern)? Those I would consider the "required" connections as the core system.

Optional "nice to have" options would be second M.2 drive in RAID with both NVME cards at full speed + full speed raid card + full speed USB-10-GiG-E.

 

[Lurick]

The chipset can provide more lanes off of it but the bandwidth (assuming 20 lanes off the chipset) from chipset to CPU is limited to those 4 PCIe 3.0 lanes.

[AquaVixen]

2 minutes ago, Lurick said:

The chipset can provide more lanes off of it but the bandwidth (assuming 20 lanes off the chipset) from chipset to CPU is limited to those 4 PCIe 3.0 lanes.

That's what I thought. So if I'm understanding the diagram correctly: Even though the PCI-Express slot off of the chipset may be PCIE-3.0-8x electrical, it can only ever have the bandwidth of PCIE-3.0-4x regardless of the physical connection on B550. I think?

[Lurick]

Just now, AquaVixen said:

That's what I thought. So if I'm understanding the diagram correctly: Even though the PCI-Express slot off of the chipset may be PCIE-3.0-8x electrical, it can only ever have the bandwidth of PCIE-3.0-4x regardless of the physical connection on B550. I think?

Yah, that's how I understand it. I believe you could use up all 20 lanes off the chipset but things would just queue up if the bandwidth was fully saturated. Not 100% on that though

[fordy_rounds]

Not an expert here, but:

1. The purpose of the chipset is (among other things) to act as a multiplexer. Essentially, it's based on the idea that most of the time, not all your lanes will be saturated. So it provides 8 lanes, and as long as they're not saturated, it can combine their traffic onto the four lanes. If they collectively get too saturated, then they'll slow down to wait for other traffic, but one or two or even four lanes can, in theory, be saturated without issue. In other words, you can use all 8 lanes, you just can't saturate all 8 lanes.

2. This depends on which port you use. Notice that the CPU can provide up to 4 10Gbps ports on its own, without the chipset. Read the MB manual to make sure you're using those ports (probably the rear-panel ports) and it won't affect your chipset bandwidth.

3. Be aware that B550 is not slated to support 3000-series APUs, and 4000-series APUs haven't come out yet. That means that, until they do, any B550 build will need a discrete GPU (or be run completely 100% headless, without even having an option to plug in a monitor for troubleshooting). Since most mini-ITX boards only have one PCIe slot, that'll leave you with nowhere to plug in the raid card. (Just because the chipset supports extra lanes, doesn't mean the motherboard has all the physical slots.) So you might need to upgrade to a micro-ATX board. (You could also get creative with M.2 to PCIe adapters, i.e. plug the dGPU into an adapter that's plugged into one of the M.2 slots—but then you're limiting your NVME storage.)

4. Finally, since storage is the main point here, I'd recommend putting your RAID card on the direct-to-CPU lanes (usually the top slot in a micro - or ATX board, and the only slot in a mini-ITX board) and your GPU in a chipset slot. That's backwards from normal, but you're not using it for heavy gaming, so it'll be fine.

 

[AquaVixen]

2 minutes ago, fordy_rounds said:

Not an expert here, but:

3. Be aware that B550 is not slated to support 3000-series APUs, and 4000-series APUs haven't come out yet. That means that, until they do, any B550 build will need a discrete GPU (or be run completely 100% headless, without even having an option to plug in a monitor for troubleshooting). Since most mini-ITX boards only have one PCIe slot, that'll leave you with nowhere to plug in the raid card. (Just because the chipset supports extra lanes, doesn't mean the motherboard has all the physical slots.) So you might need to upgrade to a micro-ATX board. (You could also get creative with M.2 to PCIe adapters, i.e. plug the dGPU into an adapter that's plugged into one of the M.2 slots—but then you're limiting your NVME storage.)

Do you have a source on this? I was under the impression that any motherboard that supports the Ryzen 3000 series will also support ALL 3000 series chips, including APU's. 

[fordy_rounds]

Just now, AquaVixen said:

Do you have a source on this? I was under the impression that any motherboard that supports the Ryzen 3000 series will also support all 3000 series chips, including APU's. 

https://www.amd.com/en/chipsets/b550

The compatibility table (you might have to scroll down a bit) shows that "2nd Gen AMD Ryzen™ Processors with Radeon™ Graphics" (which means 3000 series APUs—despite the 3, they're second-gen) are not compatible with B550 or A520.

[AquaVixen]

9 minutes ago, fordy_rounds said:

https://www.amd.com/en/chipsets/b550

The compatibility table (you might have to scroll down a bit) shows that "2nd Gen AMD Ryzen™ Processors with Radeon™ Graphics" (which means 3000 series APUs—despite the 3, they're second-gen) are not compatible with B550 or A520.

Ah, 3000 series APU's, yes. So B550 supports 3000 series (Zen2-core) non-APU processors and 4000 series (Zen3-core) non-APU processors. But not 2000 series (Zen+ core) non-APU processors. So then logically when the new 4000 series APU's come out later this year (And they are confirmed they are coming) that will be based on the Zen2 core, they most likely will be supported. So that's what I'm planning on. With the possibility to upgrade later to the 5000 series APU's based on Zen3 when they finally come out. So my plan should work fine. I'm not worried about that part. I'm not buying parts just yet. I'm trying to do the pre-purchase research part right now to find out if all of this will even work.

 

Additionally: I'm not having much luck yet finding anyone that has released or created a retail product that will provide full speed 10-GiG-E over USB-C using USB-C Gen2 10 Gbps. Does anyone know of one of these or can you find one please and link it here? I've found a Thunderbolt one from Sonnet. But that won't work on B550 motherboards as none of them have thunderbolt onboard.

[fordy_rounds]

31 minutes ago, AquaVixen said:

Ah, 3000 series APU's, yes. So B550 supports 3000 series (Zen2-core) non-APU processors and 4000 series (Zen3-core) non-APU processors. But not 2000 series (Zen+ core) non-APU processors. So then logically when the new 4000 series APU's come out later this year (And they are confirmed they are coming) that will be based on the Zen2 core, they most likely will be supported.

That's right. Glad it'll work out for you!

[AquaVixen]

Nevermind. I answered my own question in another thread by finding a different board. This thread: https://linustechtips.com/main/topic/1210379-usb-c-10-gig-e-ethernet-adapter/

 

[McBUrn]

I think going with X570 is the way to go (or server board) for this kind of project. Their advantage compared to B550 is exactly what you are looking at, having a lot of connectivity which for X570 board is achieved via this Gen4 link to the chipset.

 

To me B550 is here to offer PCIe Gen 4 to the masses while making compromises on the possibility to have multiple expansion cards/NVMe. This makes sense since the vast majority of us won't have 3 NVMe, 10HDDs and fancy RAID cards in their systems but will only stick with a boot drive a couple HDD max and a graphics card.

 

Other advantage for X570 is the CPU compatibility where 2 gen ryzen (and hence the 3x00g series), 3rg gen and upcoming 4th gen are supporting. If you need the system asap you could therefore very well go with a cheap 2nd hand 3200g until the 4x00g series comes out (year end?).