Interesting thread. My X9DRT-F doesn't have bifurcation, but then again it also doesn't have 3.3 BIOS either.
I wrote to SMC about when/if there would be a 3.3 BIOS for this model (even if its just to address Spectre/Meltdown), and the response I got was "We looked for an updated BIOS for this model and couldn't find one." No really. I had visions of people checking in desk drawers, waste baskets, and the breakroom fridge. "Say, has anybody seen a 3.3 BIOS laying around?"
One thing that may influence the "Does it or doesn't i?" question may be Supermicro's stated use cases? I know my board, at least as far as SMC is concerned, is meant to be used in half-width 1U nodes, and 1U nodes are the only compatible chassis options they list as on their site. As there's no available bifurcation riser that would work in a 1U half-width format there's no incentive for SMC to build in bifurcation (because its half width, the cards plugged into the riser need to be above the I/O ports, and a two slot riser like that simply isn't going to fit in 1U). I know people use Supermicro boards in other chassis (mine is actually in a tower case), but I doubt Supermicro spends much effort supporting them.
I suppose its remotely possible to get bifurcation on a (hypothetical) 3.3.BIOS for this board if its left over from development for a different board. But, I doubt they'd put any overt effort into it if bifurcation isn't physically possible in their stated use case.
I wrote to SMC about when/if there would be a 3.3 BIOS for this model (even if its just to address Spectre/Meltdown), and the response I got was "We looked for an updated BIOS for this model and couldn't find one." No really. I had visions of people checking in desk drawers, waste baskets, and the breakroom fridge. "Say, has anybody seen a 3.3 BIOS laying around?"
One thing that may influence the "Does it or doesn't i?" question may be Supermicro's stated use cases? I know my board, at least as far as SMC is concerned, is meant to be used in half-width 1U nodes, and 1U nodes are the only compatible chassis options they list as on their site. As there's no available bifurcation riser that would work in a 1U half-width format there's no incentive for SMC to build in bifurcation (because its half width, the cards plugged into the riser need to be above the I/O ports, and a two slot riser like that simply isn't going to fit in 1U). I know people use Supermicro boards in other chassis (mine is actually in a tower case), but I doubt Supermicro spends much effort supporting them.
I suppose its remotely possible to get bifurcation on a (hypothetical) 3.3.BIOS for this board if its left over from development for a different board. But, I doubt they'd put any overt effort into it if bifurcation isn't physically possible in their stated use case.