3 ms·

Not if you can't use them. The problem with modern PCs is lack of pcie lanes. Unless you go with Threadripper you pretty much get one GPU, two m.2 drives and on

Not if you can't use them. The problem with modern PCs is lack of pcie lanes. Unless you go with Threadripper you pretty much get one GPU, two m.2 drives and one pci slot. After that decisions have to be made on what gets disabled.

godelski 3y ago
I'm no expert here, but isn't this the number of lanes used at one time? If my understanding is correct, then generally more slots should still be better. Sure, maybe you can't write to 30 drives at the same time but who's actually doing that? You're probably reading from no more than 2 drives __at a time__. So 4 lanes per M.2 + a graphics card at 16 lanes gives you 22. Your $600 AMD Ryzen 9 7950X has 28 lanes but 22 are usable. So that of course doesn't leave you with extra lanes for other things, but that's not high end. Threadrippers have >80 lanes so... Am I misunderstanding something?
- Laforet 3y ago
  Support for PCI-E bifurcation on consumer motherboards was really good for a while when PCI-E 4.0 first came out, however it has since regressed again. Not many motherboards in the latest gen can do a proper x8+x4+x4 split. They may claim to support it but you run into weird issues has to spend weeks waiting for a bios fix. Or sometimes the support might be there but it is so poorly explained in the manual that I had to actually test it on hand to make sure that I was reading it correctly. To be fair, HEDT motherboards are not immune to this type of stupidity. However they do manage to get over these issues with the sheer number of lanes.
- wtallis 3y ago
  AMD's mainstream desktop platform effectively has four more PCIe lanes coming out of the CPU socket than Intel's mainstream desktop platform. Both then have a variable number of PCIe lanes fanned out from the chipset and sharing that chipset's uplink to the CPU. (Intel has a range of chipsets with different number of lanes enabled, and AMD's more expensive chipset solution is to daisy-chain a second chipset).
arcticbull 3y ago
Sort of, there's also dedicated PCIe lanes (on AMD) or DMI lanes (on Intel) to the southbridge which fans them out to additional lanes for devices.

godelski 3y ago

I'm no expert here, but isn't this the number of lanes used at one time? If my understanding is correct, then generally more slots should still be better. Sure, maybe you can't write to 30 drives at the same time but who's actually doing that? You're probably reading from no more than 2 drives __at a time__. So 4 lanes per M.2 + a graphics card at 16 lanes gives you 22. Your $600 AMD Ryzen 9 7950X has 28 lanes but 22 are usable. So that of course doesn't leave you with extra lanes for other things, but that's not high end. Threadrippers have >80 lanes so... Am I misunderstanding something?

Laforet 3y ago
Support for PCI-E bifurcation on consumer motherboards was really good for a while when PCI-E 4.0 first came out, however it has since regressed again. Not many motherboards in the latest gen can do a proper x8+x4+x4 split. They may claim to support it but you run into weird issues has to spend weeks waiting for a bios fix. Or sometimes the support might be there but it is so poorly explained in the manual that I had to actually test it on hand to make sure that I was reading it correctly. To be fair, HEDT motherboards are not immune to this type of stupidity. However they do manage to get over these issues with the sheer number of lanes.
wtallis 3y ago
AMD's mainstream desktop platform effectively has four more PCIe lanes coming out of the CPU socket than Intel's mainstream desktop platform. Both then have a variable number of PCIe lanes fanned out from the chipset and sharing that chipset's uplink to the CPU. (Intel has a range of chipsets with different number of lanes enabled, and AMD's more expensive chipset solution is to daisy-chain a second chipset).

arcticbull 3y ago

Sort of, there's also dedicated PCIe lanes (on AMD) or DMI lanes (on Intel) to the southbridge which fans them out to additional lanes for devices.