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The vast majority of people run just one gpu, which motherboards have a dedicated direct to CPU x16 slot for. Stealing lanes comes into play with chipset connec
by Numerlor 1y ago
The vast majority of people run just one gpu, which motherboards have a dedicated direct to CPU x16 slot for. Stealing lanes comes into play with chipset connected slots
- doubled112 1y agoThe real PITA is when adding the NVMe disables the SATA ports you planned to use.
- creatonez 1y agoDoesn't this usually only happen when you put an M.2 SATA drive in? I've never seen a motherboard manual have this caveat for actual NVMe M.2 drives. And encountering an M.2 SATA drive is quite rare.
- ZekeSulastin 1y agoI have a spare-parts NAS on a Z170 (Intel 6k/7k) motherboard with 8 SATA ports and 2 NVME slots - if I put an x2 SSD in the top slot it would disable two ports, and if it was an x4 it would disable four! Luckily the bottom m2 slot doesn’t conflict with any SATA ports, just an expansion card slot. (The board supports SATA Express even - did anything actually use that?) SATA ports are far scarcer these days though and there’s more PCIE bandwidth available anyways, so it’s not surprising that there aren’t conflicts as often anymore.
- toast0 1y agoNope, for AM5, both of the available chipsets[1] have 4 serial ports that can be configured as x4 pci-e 3.0, 4x sata, or two and two. I think Intel does similar, but I haven't really kept up. [1] A620 is cut down, but everything else is actually the same chip (or two)
- zten 1y agoI bought a Gigabyte X870E board with 3 PCIe slots (PCIe5 16x, PCIe4 4x, PCIe3 4x) and 4 M.2 slots (3x PCIe5, 1x PCIe 4). Three of the M.2 slots are connected to the CPU, and one is connected to the chipset. Using the 2nd and 3rd M.2 CPU-connected slots causes the board to bifurcate the lanes assigned to the GPU's PCIe slot, so you get 8x GPU, 4x M.2, 4x M.2. I wish you didn't have to buy Xeon or Threadripper to get considerably more PCIe lanes, but for most people I suspect this split is acceptable. The penalty for gaming going from 16x to 8x is pretty small.
- elevation 1y agoEven with a Threadripper you're at the mercy of the motherboard design. I use ROG board that has 4 PCIe slots. While each can physically seat an x16 card, only one of them has 16 lanes -- the rest are x4. I had to demote my GPU to a slower slot in order to get full throughput from my 100GbE card. All this despite having a CPU with 64 lanes available.
- nrdvana 1y agoYou're using 100GbE ... in an end-user PC? What would you even saturate that with?
- aaronmdjones 1y agoI wouldn't think it's about saturating it during normal use; rather, simply exceeding 40 Gbit/s, which is very possible with solid-state NASes.
- Dylan16807 1y agoOkay, but then I need to ask what kind of use case doesn't mind the extra latency from ethernet but does care about the difference between 40Gbps and 70Gbps.
- grw_ 1y agoI don't think Threadripper platform is to blame that you bought a board with potentially the worst possible pcie lane routing. Latest generation has 88 usable lanes at minimum, most boards have 4x 16x, and Pro supports 7x Gen 5.0 x16 links, an absolutely insane amount of IO. "At the mercy of motherboard design"- do the absolute minimum amount of research and pick any other board?
- ciupicri 1y agoFor a moment I didn't believe you, then I looked at the X870E AORUS PRO ICE (rev. 1.1) motherboard [1] and found this: > 1x PCI Express x16 slot (PCIEX16), integrated in the CPU: > AMD Ryzen™ 9000/7000 Series Processors support PCIe 5.0 x16 mode > * The M2B_CPU and M2C_CPU connectors share bandwidth with the PCIEX16 slot. > When theM2B_CPU orM2C_CPU connector is populated, the PCIEX16 slot operates at up to x8 mode. [1]: https://www.gigabyte.com/Motherboard/X870E-AORUS-PRO-ICE-rev-11/sp#sp https://www.gigabyte.com/Motherboard/X870E-AORUS-PRO-ICE-rev...
- viccis 1y agoAs some others have pointed out, there are some motherboards in which, if you use M.2 cards on the wrong slot, it will turn your 16x GPU slot into 8x.