Device fails to connect to the second PCIe port.
Device fails to connect to the second PCIe port.
I just added a bifurcation chip to my streaming PC to maximize performance with old capture gear. Currently, I’m facing problems with the second capture card in the chip. My system runs Windows 10 with a Ryzen 3700X, 32GB RAM, GTX 1060, and a Gigabyte X570 GPU. The motherboard has a JMT PCI-E bifurcation chip with a SATA power port. I’ve connected the PC to the BIOS, set the chipset from BIF to 2x8, and placed both capture cards in the riser cable. When I boot, the first slot (closest to the PCIe connection) works perfectly, but the second slot only shows the card in its "first" position and doesn’t register it at all. The second slot has power and is partially functional. Placing the 4K Pro Mk2 in the second slot sends the HDMI signal through fine. I’ve tried swapping which capture card goes into each slot, but the first slot always works instantly while the second remains unresponsive. I’m unsure if I’m changing the BIOS settings incorrectly. Should I connect a SATA power cable to the bifurcation chip from the PSU? Is there another way to configure the x16 slot as x8x8 that I might be missing?
You can observe the basic design by examining the rear. It clearly shows the layout of the first eight fingers connecting to one slot, another eight going to the opposite slot, and a timing chip that draws power from the SATA power connector instead of the slot itself
The bifurcation you're using is set up for just the first slot. If you have components in both "x16" slots, only one slot will be available—x8. Since this riser connects to an x8 on the motherboard, it only passes through that single x8. You might be able to adjust this by locating an x4 version of the same riser, provided the BIOS supports x8/x4/x4 configurations.
The attempt to connect SATA power to the back of the unit didn’t resolve the problem. My GPU is in the second "x16" slot, which should be a full-length x4 PCIe port according to the manual. When you mention a riser, you’re referring to the JMT expansion card or the Okinos Riser cable. I also captured a screenshot of the BIOS and selected the 2x8 bifurcation option. However, it didn’t work, so I went through each setting and none resolved the issue. Is setting the bifurcation to 2x8 correct? I assumed it would direct the PC to split only the first x4 slot into an x8 slot, but the manual lists options like Auto, 2x8, 1x8/2x4, 4x4, with a default of Auto.
Looks like you're questioning the compatibility details, but the specs say this part works with your setup. The user confirms it's listed as compatible and shares positive experiences from others. It seems the issue might be elsewhere or in testing.
For this dedicated streaming setup, I placed the GPU in the lower slot since I don’t require heavy performance. The splitter return is active, and I’m testing the x16tox4x4x4x4 chipset configuration. Capture cards will operate at x4 speeds as specified, which should prevent bottlenecks if successful. This setup also lets me expand capture inputs later if needed. If not, I’ll discard the riser components and stick with one capture card.
Here’s a revised version of your message:
I wanted to wrap up this thread with the answer I discovered. In short, I updated the BIOS from the original release to the latest version and indicated which generation the x16 slot should support. While exploring the BIOS, I realized I was still using the older version. I contacted Gigabyte and updated both the chipset drivers and the BIOS to the newest releases (switched from 2019 to 2024 drivers). New settings became available that let me explicitly define the PCIE lane generation. I changed the bifurcation setting to 4x4 after finding the matching chip, kept the PCIE generation as auto, and it worked perfectly. The original 2x8 chip would have been fine, but it’s now in a box and being sent back to Amazon. On the plus side, I now have two free PCI-E slots available for future expansion cards if my streaming PC ever needs more upgrades.