Soldato
before anyone says RTFM I have and it was useless 
i.e didn't actually give me a concrete answer, and reading the asus PCIe bifurcation tables melted my eyes and significant portions of my brain.......
If i understand correctly the 7800x3d has a total of 24 lanes that it can assign.
the B650E-i motherboard has a pcie5.0 M2 slot and a pcie 4.0 slot and a pcie x16.1 slot for a GPU
4 lanes are dedicated to the motherboard/chipset, so total lanes available to user are 20
therefore if you place a pcie 5 GPU in the x 16 you can still use the pcie 5.0 m2 slot and that would be the 20 lanes left gone.
or you could put a GPU in x16.1 and an m2 drive in the M2.2 slot which is pcie 4, and that is the 20 lanes gone
Motherboard manual states that the Pcie lanes for m2.1 and m2.2 are from ryzen 7000 so from CPU
therefore max load out for this board on PCIe would be a GPU x 16 and an one m2 drive in which ever slot you wanted.
If you try and populate both m2 slots you would then have you GPU running at x8 and not x 16
The mother board does not have any M2 slots that get lanes from chipset as it is a mini itx 650E so it only has 2 M2 one PCIe 4 and one PCIe 5 and they are botrh listed as getting lanes from Ryzen 7000
does that make sense ??
If that is correct I guess I can then extrapolate this logic for any other mother board based on where its PCIe lane allocaitons come from i.e if it has 4 and m2.1 and m2.2 are linked to ryzen 7000 then the same applies i.e can only use one of them to get full bandwidth to GPu, and if m2.3 and m2.4 are PCIe 4.0 and listed against chipset I can populate both of them with no hit to a single GPU but if I populate PCIe 16.2 i.e 2nd GPU then that GPU would also end up running at x 8 unless the chipset had 24 lanes to allocate ?
as you can tell I am not good at this stuff.
so if that is also correct, technically if you run a mini itx set up you are only ever going to be able to use 1 M2 slot and if full ATX with 4 M2 slots you probably can only run 3 unless the PCIe lane allocations are stated differently in the manual i.e 1 m2 slot comes from CPU and the other 3 are Chipset then you could run 4 M2 drives and 1 GPU all at max bandwidth ?
sorry of that was a long post of nonsense
i.e didn't actually give me a concrete answer, and reading the asus PCIe bifurcation tables melted my eyes and significant portions of my brain.......If i understand correctly the 7800x3d has a total of 24 lanes that it can assign.
the B650E-i motherboard has a pcie5.0 M2 slot and a pcie 4.0 slot and a pcie x16.1 slot for a GPU
4 lanes are dedicated to the motherboard/chipset, so total lanes available to user are 20
therefore if you place a pcie 5 GPU in the x 16 you can still use the pcie 5.0 m2 slot and that would be the 20 lanes left gone.
or you could put a GPU in x16.1 and an m2 drive in the M2.2 slot which is pcie 4, and that is the 20 lanes gone
Motherboard manual states that the Pcie lanes for m2.1 and m2.2 are from ryzen 7000 so from CPU
therefore max load out for this board on PCIe would be a GPU x 16 and an one m2 drive in which ever slot you wanted.
If you try and populate both m2 slots you would then have you GPU running at x8 and not x 16
The mother board does not have any M2 slots that get lanes from chipset as it is a mini itx 650E so it only has 2 M2 one PCIe 4 and one PCIe 5 and they are botrh listed as getting lanes from Ryzen 7000
does that make sense ??
If that is correct I guess I can then extrapolate this logic for any other mother board based on where its PCIe lane allocaitons come from i.e if it has 4 and m2.1 and m2.2 are linked to ryzen 7000 then the same applies i.e can only use one of them to get full bandwidth to GPu, and if m2.3 and m2.4 are PCIe 4.0 and listed against chipset I can populate both of them with no hit to a single GPU but if I populate PCIe 16.2 i.e 2nd GPU then that GPU would also end up running at x 8 unless the chipset had 24 lanes to allocate ?
as you can tell I am not good at this stuff.
so if that is also correct, technically if you run a mini itx set up you are only ever going to be able to use 1 M2 slot and if full ATX with 4 M2 slots you probably can only run 3 unless the PCIe lane allocations are stated differently in the manual i.e 1 m2 slot comes from CPU and the other 3 are Chipset then you could run 4 M2 drives and 1 GPU all at max bandwidth ?
sorry of that was a long post of nonsense
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