PCIe x16 bifurcation to x4x4x4x4 then mixing Gen2 and Gen3 cards - will all be Gen2 speed?

[petreza]

Does anyone know if the bifurcation specification requires that all the bifurcated channels must have independent timing? That is, if I bifurcate a x16 Gen 3.0 slot into x4x4x4x4 and then plug three Gen3 and one Gen2 cards, will all four cards operate at Gen2 speeds?

Thanks!

 

[petreza]

asked Supermicro; they said they do not know - have never tested such a setup - but in general they think one card should NOT affect the speed of another even if they are plugged in the same slot (using bifurcation and passive slot splitters)

 

[Kev]

Should not affect anything because the negotiation of the speed is done at the RC, root complex and each device is connected to a dedicated foot complex. This is purely from a system engineering point of view.

 

[MiniKnight]

I'd think not, but this is one I'd like to hear what you find.