PCI- E 16x splitters

[Sam F]

I was wondering if anybody knows how to get 16x PCI-E into two 8x PCI-E for a gpu server?

[emosun]

it would be far easier to use a board with two 8x slots as only needing two slots is pretty common

[Sam F]

3 hours ago, emosun said:

it would be far easier to use a board with two 8x slots as only needing two slots is pretty common

but i am putting 8x gpu's in it that need 8x each, no motherboard for trx40 has 8 pcie slots at 8x

[Grabhanem]

IIRC TRX40 is only 60 pcie lanes direct from the CPU, so you can't run 8 cards at 8x anyway.

 

What is this for?

[Sam F]

3 hours ago, Grabhanem said:

IIRC TRX40 is only 60 pcie lanes direct from the CPU, so you can't run 8 cards at 8x anyway.

 

What is this for?

but does any motherboard have 8 pci-e slots ?

[WereCatf]

2 minutes ago, Sam F said:

but does any motherboard have 8 pci-e slots ?

There's one mobo with 18 PCIe x1 - slots and one PCIe x16 - slot that I know of: https://www.asus.com/Motherboards/B250-MINING-EXPERT/

[Grabhanem]

40 minutes ago, Sam F said:

but does any motherboard have 8 pci-e slots ?

Epyc or Xeon boards would probably be your best bet. A lot of those have full 16x slots in every possible position (7 for ATX) but you could also break out U.2 ports to PCIe and/or use bifurcating splitters, which tend to be more validated for server boards, to get an 8th slot.

 

This is one example-- 7x16 pcie 4.0 and a few U.2 and M.2 ports for 7002 series Epyc:

https://www.newegg.com/asrock-rack-romed8-2t/p/N82E16813140044

[jimm_eh]

On 9/26/2020 at 9:36 AM, Grabhanem said:

IIRC TRX40 is only 60 pcie lanes direct from the CPU, so you can't run 8 cards at 8x anyway.

 

What is this for?

Not sure about OP, but professional VFX work using GPU renderers like Redshift would love to have 8x GPU's available.  I'll be building a workstation with this in mind pretty soon (hence my interest in this thread), though I think 4x3090's would be enough for my purposes.

[Grabhanem]

3 hours ago, jimm_eh said:

Not sure about OP, but professional VFX work using GPU renderers like Redshift would love to have 8x GPU's available.  I'll be building a workstation with this in mind pretty soon (hence my interest in this thread), though I think 4x3090's would be enough for my purposes.

I'm not saying there's no purpose for 8GPU-- you just physically can't run 8 GPUs at x8 off a TRX40 board without some serious server-grade stuff, since there's not enough PCIe lanes. You can get PLX expanders etc to get more lower-spec PCIe lanes, but at that point you're best off just going with Epyc.