Limit to the number of PCIe devices allowed in a system?

[VPITV]

Hello,

We build PCIe cards with a 12 port switch (1 upstream and 11 downstream) that connects to 10 downstream PCIe devices.  We are finding that the number of such PCIe devices we can have on the bus is limited to something like 54.  Is there a way to change this?

The system will not even POST when this number is exceeded.

We would like to have as many as 80 devices on the PCIe bus.  The PCIe spec allows for up to 255 devices.  Is this a limitation imposed in the BIOS or elsewhere?  Any workarounds for this?

TIA

-Tom

[gorka_pr]

sometimes is the CPU limiations, for example the Intel Core i5-6400 only support 16 lanes. so if you want to put a GPU and a PCI-E USB card, for example, the GPU is x16 (16 lanes) and the USB card is x4, the GPU will go down to x8.