Blackmagic Forum

Hey,

Im a editer/ live stream producer, I know computers quite well but have never built one before. My plan was to build a live streaming/editing rig with multiple capture cards/network cards. I used a well compiled guide I found on reddit to create a video editing rig. I saw amount of pcie slots on the motherboard & thought I could just add in pcie captures cards as I please....however I now realise this may not be possible due to PCIE lanes.

I have purchased all the parts: i9 12900k, 3070 RTX, z690 Gaming x DDR4 Motherboard, 64gb DDR4 ram, 1 ssd, 2x m.2 ssd & a Decklink 8k Capture card.

I have purchased an 8k Decklink pro with the intention of doing 1080p streaming with the occasional 4k source scaled up. When I will be live streaming I will not be using the m2's ssd or if I do they will only be recording a feed or two.

Will the 8k capture card bottleneck in this setup capturing saying 4x4k 25p cameras? Would I be better off getting a quad 2 would that run better?

I have heard I could run my graphics card in 8x but not really what that means. I understand that running stuff all together could cause a bottleneck but I am willing to move stuff around between say a "live setup" & an "edit" setup to make sure things work smoothly for each application.

Thanks any help can be appreciated.

You should be ok provided that you only plan to do 4x 4K capture up to 25 or 30fps.

The Intel Z690 chipset architecture has 20 PCIe Lanes connected directly to the CPU (16 PCIe 5.0 lanes typically for a graphics card and 4 PCIe 4.0 lanes typically for SSD storage). And then it has up to 28 additional PCIe Lanes connected to the chipset (up to 12 PCIe 4.0 lanes and 16 PCIe 3.0 lanes). Various other components like USB ports, Ethernet ports, etc. also go through the chipset and will share bandwidth with PCIe cards connected to the chipset's PCIe lanes. Here's a block diagram of the Z690 architecture:
https://www.servethehome.com/intel-12th ... k-diagram/

For the Gigabyte Z690 Gaming X Motherboard you mentioned, the first PCIe slot (PCIEX16) is the one that uses the 16 PCIe 5.0 lanes to the CPU and is where you would typically put your graphics card. That leaves 2 more PCIe slots that are 16 lane mechanical slots (so x16 PCIe cards or smaller will fit), but in terms of bandwidth, each slot only supports 4 lanes of PCIe 3.0.

So you might think that this would cause a problem for the DeckLink 8K Pro card which recommends using an 8 lane PCIe 3.0 slot. But the card will really only use the full bandwidth of the PCIe 3.0 x8 interface if you are using the maximum video input or output capabilities of the card for 4x 12G SDI video signals (four 4K 60fps channels or one 8K 60fps channel). The bandwidth of a PCIe 3.0 x8 interface is roughly 63 Gb/s and the bandwidth of 4x 12G SDI video is roughly 4 x 12Gbps or 48 Gbps.

But if you are only doing four 4K feeds at 25 or 30 fps, you are only using the 6G SDI standards and the overall bandwidth needed would be about 4 x 6Gbps or 24 Gbps which would fit within the 31.5 Gb/s throughput supported by a PCIe 3.0 x4 interface.

Now, if at some point in the future, you decide you do have a need to do 4x 4K feeds at 50 or 60 fps, then you could run into an issue if you put the DeckLink card in one of the slots with PCIe x4 bandwidth. And unfortunately on that motherboard, those two slower slots do not seem to be configurable at all (so you couldn't say run one at PCIe x8 and disable the second). In that case your only option would be to use the PCIe bifurcation option in the BIOS to subdivide the PCIe x16 slot (used for the graphics card) into two PCIe x8 slots. To make this work you would need a PCIe x16 riser card/cable that plugs into the motherboard slot and provides two mechanical slots for connecting cards. And then you would enable the PCIe x8/x8 bifurcation option for that first slot. Then both the graphics card and DeckLink card would share the 16 PCIe lanes to the CPU (with each getting 8 of them). In that case the graphics card could run a bit slower (for operations requiring a lot of throughput), but the DeckLink card would have the bandwidth it would need for 4 x 12Gbps of video data.

It's also worth pointing out that the limitation in this case is not actually the Z690 chipset itself. There are enough PCIe lanes connected to the Z690 chipset (and enough bandwidth in the DMI 4.0 x8 interface between the chipset and CPU) for the DeckLink 8K to work (even at its maximum video capture throughput) connected to the chipset PCIe lanes. The issue is how that particular motherboard allocated the chipset PCIe lanes to the PCIe slots and other devices. It's possible that another Z690 motherboard with fewer PCIe slots or more configurability would allow for a PCIe 3.0 x8 slot to the chipset.

But again, if you're going to stick to 4x 4K at 30fps or less, you really only need PCIe 3.0 x4 bandwidth and should be ok.

Dave Del Vecchio wrote:You should be ok provided that you only plan to do 4x 4K capture up to 25 or 30fps.

The Intel Z690 chipset architecture has 20 PCIe Lanes connected directly to the CPU (16 PCIe 5.0 lanes typically for a graphics card and 4 PCIe 4.0 lanes typically for SSD storage). And then it has up to 28 additional PCIe Lanes connected to the chipset (up to 12 PCIe 4.0 lanes and 16 PCIe 3.0 lanes). Various other components like USB ports, Ethernet ports, etc. also go through the chipset and will share bandwidth with PCIe cards connected to the chipset's PCIe lanes. Here's a block diagram of the Z690 architecture:
https://www.servethehome.com/intel-12th ... k-diagram/

For the Gigabyte Z690 Gaming X Motherboard you mentioned, the first PCIe slot (PCIEX16) is the one that uses the 16 PCIe 5.0 lanes to the CPU and is where you would typically put your graphics card. That leaves 2 more PCIe slots that are 16 lane mechanical slots (so x16 PCIe cards or smaller will fit), but in terms of bandwidth, each slot only supports 4 lanes of PCIe 3.0.

So you might think that this would cause a problem for the DeckLink 8K Pro card which recommends using an 8 lane PCIe 3.0 slot. But the card will really only use the full bandwidth of the PCIe 3.0 x8 interface if you are using the maximum video input or output capabilities of the card for 4x 12G SDI video signals (four 4K 60fps channels or one 8K 60fps channel). The bandwidth of a PCIe 3.0 x8 interface is roughly 63 Gb/s and the bandwidth of 4x 12G SDI video is roughly 4 x 12Gbps or 48 Gbps.

But if you are only doing four 4K feeds at 25 or 30 fps, you are only using the 6G SDI standards and the overall bandwidth needed would be about 4 x 6Gbps or 24 Gbps which would fit within the 31.5 Gb/s throughput supported by a PCIe 3.0 x4 interface.

Now, if at some point in the future, you decide you do have a need to do 4x 4K feeds at 50 or 60 fps, then you could run into an issue if you put the DeckLink card in one of the slots with PCIe x4 bandwidth. And unfortunately on that motherboard, those two slower slots do not seem to be configurable at all (so you couldn't say run one at PCIe x8 and disable the second). In that case your only option would be to use the PCIe bifurcation option in the BIOS to subdivide the PCIe x16 slot (used for the graphics card) into two PCIe x8 slots. To make this work you would need a PCIe x16 riser card/cable that plugs into the motherboard slot and provides two mechanical slots for connecting cards. And then you would enable the PCIe x8/x8 bifurcation option for that first slot. Then both the graphics card and DeckLink card would share the 16 PCIe lanes to the CPU (with each getting 8 of them). In that case the graphics card could run a bit slower (for operations requiring a lot of throughput), but the DeckLink card would have the bandwidth it would need for 4 x 12Gbps of video data.

It's also worth pointing out that the limitation in this case is not actually the Z690 chipset itself. There are enough PCIe lanes connected to the Z690 chipset (and enough bandwidth in the DMI 4.0 x8 interface between the chipset and CPU) for the DeckLink 8K to work (even at its maximum video capture throughput) connected to the chipset PCIe lanes. The issue is how that particular motherboard allocated the chipset PCIe lanes to the PCIe slots and other devices. It's possible that another Z690 motherboard with fewer PCIe slots or more configurability would allow for a PCIe 3.0 x8 slot to the chipset.

But again, if you're going to stick to 4x 4K at 30fps or less, you really only need PCIe 3.0 x4 bandwidth and should be ok.

Wow thanks so much, explained it really well.

So would I be able to add another 8k pro or core duo 2 to the additional free pcie x16 slot & it would run at x4 or would that be too much for the cpu?