Upper PCIe slot has only x4 PCIe lanes which is exactly what is needed for single M.2 NVMe drive.Chipset/PCH has PCIe Gen2 standard (x8 lanes) while CPU normally has faster PCIe Gen3 versionThere's a hardware detection program called HWINFO64 which can show you a tree-map of your PCI-e bus devices like this (it's not T3600 machine) [IMAGE]   As you can see on segment marked as (A and B) - NVidia card and M.2 storage device are connected directly via CPU (Rocket Lake CPU) PCI bus and device C is connected via PCH PCIe lanes (SD card-reader).HWInfo64 can also show you info on slot capabilities (maximum link supported) and device information used on that slot (current link speed and lanes used).As for adapter card detection mentioned by [NAME] de Oro  I don't think it matters as PCIe lanes wiring is pretty much standard 1-to-1 connection pinout (4 pins for each PCIe lane - Rx and Tx signal pairs {in and out, or + and -}) but the problem might be if it has extra controller on board (which for M.2 NVMe adapters is hardly a case except for RAID or hardware level active-type bifurcation) - then it's up to CPU and BIOS to decide whether to allow PCIe to work (on consumer products Intel has designed some architectures the way for CPU PCIe lanes to work only with Storage and GPU devices, Dell is normally adding extra layer of restrictions via BIOS to limit what kind of cards can be inserted there, this might be the case since blue PCIe port on your motherboard is said to be for GPU in Dell manual).If your adapter is x16 PCIe with x4 NVMe M.2 cards then slot should support PCIe lanes bifurcation (automatic or manual configuration via BIOS, on server boards there are normally options like Auto, x16, x8x8, x8x4x4, x4x4x8 , x4x4x4x4).But I guess (as per your link to adapter) you're using single slot M.2 adapter therefore most of above won't matter anyways, especially considering what T3600 is more of a server-grade platform with much less restrictions on PCIe devices used and NVidia GTX 1060 being a lower-end card with very limited actual bandwidth requirements (GB/s) for PCIe width (therefore x4 lanes is normally not a bottleneck).
I'd like to install a PCIe to M2 adapter in my T3600. There are two x16 ports on the 8HPGT, but I would have to install the adapter in the top slot to keep from totally blocking my GPU fan. I can't find information on whether or not the second x16 is still connected directly to the CPU or if it runs through the PCH.  I don't want to strangle my GPU bandwidth, and if I have to, I guess I'd rather run the M2 adapter through an x4 port. Just wondering if that's what it'll come down to.
T3600- 8HPGT PCIe3x16 specs