

The GTX 1650 I think is limited to 2 or 4 transcodes by nvidia, as far as I’ve heard the Intel iGPUs since 7th gen can handle up to 20 1080p transcodes, or around 5 4k transcodes.
I think you’re off by 8 on your PCIe bandwidth due to conversion between bytes and bits, PCIe 3.0 x1 can do 1GB/s or 8Gb/s half-duplex, 16Gbps full-duplex. PCIe 3.0 x4 is 32Gbps/64Gbps.
So the 10GbE card would be fine in the x4 slot (and pretty close to full speed in x1 even), and the SAS card in the x1 slot would get you 5 HDDs at full speed of 200MB/s each. Not sure how many HDDs you need to hook up though.
It also depends on the chipset, it looks like B760 maybe supports PCIe 4.0 on all the slots, so double the bandwidth for the x4 and x1 slots vs PCIe 3.0. The higher end Z790 chipsets have even more PCIe 4.0 lanes: https://www.gizmowind.com/b760-vs-z790/
Plus keep in mind the other reason the PCIe slots might seem limited is the onboard M.2 slots are using PCIe lanes as well, vs using an addon card in a PCIe x16 slot. Some of the Z790 boards have 4x onboard M.2 NVMe slots.
Glad I could help!
Double check the specific motherboard specs too, even though Z790 has more lanes, some boards may only have 1 x16 slot still.