PCIe split 4x4x4x4 from an x16 port
PCIe split 4x4x4x4 from an x16 port
Hey! I just purchased an ASUS X16 to 4x M.2 NVMe drive for my NAS setup using a 4x1TB Intel 660P processor. I considered connecting it to my 24/7 PC with a Ryzen 2200G ASRock X370 mini-ITX. EDIT: my "24/7" system doesn’t have a dedicated graphics card—it only has the 2200G, an ASRock X370 mini-ITX, a 120GB SSD, some HDDs, and 8GB RAM. It’s been used as a testing server for websites, FTP servers, databases, etc. After some trial and error, I realized it wasn’t as straightforward as I thought. Initially, only one SSD worked until I discovered an option in the BIOS to split the X16 PCIe into separate x4 slots or two x8 slots, which allowed another SSD to connect. Through some research, I learned this technology is called PCIe bifurcation. It seems my motherboard was lucky to support two SSDs, as others mentioned only ASRock offers this feature on certain AM4 boards (besides Brother’s B350 version). If a 4x4x4x4 split isn’t available on this board or another AM4 model, what consumer platforms or motherboards support PCIe bifurcation for this purpose?
Could you explain what you mean by daily driver? Does it imply having a GPU along with a GPU? That’s feasible but would need some adjustments. The Ryzen consumer model offers 20 PCIe lanes—4 for NVMe and 16 for other slots. Using a PCIe 16x slot for an M.2 card in 16x mode lets you connect all M.2 devices. You’d need to use the listed card to enable GPU operation in 4x mode from the CPU-mounted slot. This setup would result in reduced performance.
I probably have made this part a little unclear. It is an PC thats only used for minior things like as a apache server for testing websites or other similar things, it is running 24/7. It is not used as an user PC. (I will update the main post) But how do I do that? The BIOS I have got at the moment only can do two time 8 lanes as I understand it.
When no other device is connected, the card should operate in 16x mode on the top slot. Without a video output, verifying this requires using a GPU via the M.2 slot. After confirming, it appears the system is only supporting 8 lanes in 8x8 mode, meaning the motherboard is multiplexing it into 16x 2.0 lanes. This setup would enable functionality, but you'd need a second M.2 card to achieve it. I haven't found any multiplex cards yet.
Thats a bummer, also the 2400G has only 8 lanes dedicated to the x16 Slot and I do not think there is any CPU for the AM4 sockel with integrated graphics and 16 lanes for the x16 Slot. What do you mean wit an second m.2 card? If I remember correctly, I heard that Zen3 will support PCIe 4.0. with that it would be possible to run their low end 3200G with 8 x PCIe 4.0 lanes multiplexed to 16x PCIe 3.0 Lanes?
Sure, I picked up that lesson the other way ^^. Thanks for bringing it to my attention—I made the necessary changes to the main post.
The first card can support two devices because it only has eight lanes. You'll need a second card. This is possible in theory, but we're unsure if mobile vendors will handle it, and KTS is unlikely. If you're aiming for a multiplex card, you'll have to invest in server hardware. When does a threadripper become more affordable? You can find MATX threadripper boards.
Hi Chaftalie, I'm working with the ASRock X570m Pro4. https://www.asrock.com/mb/AMD/X570M Pro4/ 1x16 -> 4x4. The bifurcation settings were added in BIOS version 2.21 on 2019/11/25. The board also supports ECC memory without buffering. I'm currently using it with this card. https://www.asrock.com/mb/spec/product.asp?Model=ULTRA QUAD M.2 CARD
Racom, thanks for the message. I'm having trouble locating a microATX motherboard that supports 4x4 bifurcation. Could you let me know what CPU model you're using? Also, do you plan to run a discreet GPU alongside the Asus Hyper card, or would you need to swap components to save PCIe lanes?
Both X470 AsrockRack boards support their x16 as 4x4 expansion slots. The user manual mentions this detail on the second page, excluding the index pages. For the X470D4U2-2T model with double 10Gbit LAN, Asrock provides a compatibility list for its quad M2 cards. However, this list lacks many Asrock boards, as seen with the X470 and X570 models that work with 4x4 slots. In November, I reached out to their support, but they couldn’t supply a complete list of all compatible boards. You can run a dedicated GPU from another PCIe slot (through the chipset) or use an M2 to PCIe adapter if you really need a GPU on a microATX board.