Sorry to dig up this old thread, but my question relates to the OP. I am running a similar setup as OP with a I5-7400 and iGPU along with a nVidia GTX 1060 3gb dGPU. I had to manually enable the iGPU in bios so they both run in tandem.

That being said, how do I confirm that encoding has been offloaded from the CPU onto the iGPU? When I look at task manager performance tab the iGPU appears dormant, no activity. However, the CPU used to peg at 100% while gaming and now it dips into the 70's and 80's once I activated the iGPU so I have a suspicion the iGPU is engaged. Is there another way to confirm?

Edit: Forgot to include that I'm running a Dell D6000 via USB-C on Windows 10 (whatever latest public version is) and dual monitors at 1080P.