Question The PCIe port bifurcation does not work in my system. System: SuperMicro PC with motherboard X9DRi-F rev:1.11A, latest BIOS X9DRi5_709 (version 2.15.1236 from AMI) The PCIe slot is set in x8x8 bifurcation mode. My adapter: includes PEX8734 in switch Non-Transparent virtual switch mode. The 8734 is configured as two independent virtual switches (much like depicted Product_Brief_PEX_8734_v1-1_04Oct13.pdf Figure 4a). Only one of the two 8 lane interface towards the CPU is recognized by the BIOS (lspci is used). It seems like both virtual switches in 8734 are configured correctly as both ports towards the CPU can be recognized – but not at the same time. The upper 8 lanes are recognized by the BIOS when a x8x8 lane slot is used. When I insert a 8-lane PCIe riser board in the PCIe-slot, then the lower 8 lanes of the PLX is recognized. Answer We don't enable it in the default BIOS, please contact Tech Support for BIOS to support this feature. Was this FAQ helpful? YES      NO Enter Comments Below: Note: Your comments/feedback should be limited to this FAQ only. For technical support, please send an email to support@supermicro.com.  Enter your email address below if you'd like technical support staff to reply:  Please type the Captcha (no space) N K 7 F FAQ Stats FAQ ID Related Category / Keyword Date Posted Code 22573 BIOS: - AMI BIOS 02/26/16     Print Answer