Does the "Precision 7875 Tower Workstation" support PCIe bifurcation 16x -> 8x+8x ?

Check in your system BIOS settings.  If the option is not there, it does not.

Hi Chino,
thanks for the reply.

I don't have this WS in my availability,  I'm considering its purchaising just now.
My old Dell Tower 5810 does work well with 8x+8x bifurcation, at least with my specific hw expansion, but it's quite difficult to find this specific information for the new models.

In any case, I would be able to look inside the BIOS image file available in one of the following formats:
.rom, .bin, .cap, ,scap, .bio, .fd, .wph, .dec
but the Dell website only provides the .RCV format and my analysis flow doesn't work with it.
Now I'm trying to convert the .rcv to one of the above formats... without any success.

If it helps, here is the user manual for T7875  https://www.dell.com/support/manuals/en-us/precision-t7875-workstation/owners_manual_tramore_precision_7875_tower/specifications-of-precision-7875-tower?guid=guid-7c9f07ce-626e-44ca-be3a-a1fb036413f9&lang=en-us

With two PCIe x16 slots, very likely that one being used for graphics card, that left one with 16 lanes for bifurcation applications.  There is optional Ultra Speed Quad being offered for this system.  Am going to throw in my guess here that the PCIe x16 slots have native x4 x4 x4 x4 bifurcation in order to support and recognize four NVMe drive on the adapter.

unfortunately the manual (I had seen it) does not contain any useful information.
I agree with you about the x4x4x4x4 bifurcation, otherwise the Ultra Speed ​​Quad card would not work. but there are MBs with only the x4x4x4x4 bifurcation, one is the ASUS Pro WS TRX50-SAGE WIFI, no support for x8x8 there (I looked inside the BIOS and checked with their tech support).

I forwarded the question to a Dell dealer...hoping he can answer