PC config: i7-8700 (Intel HD Graphics 630), AMD RX 580, 32GB, 2 fast M.2 SSDs, one 40" monitor on the RX 580, nothing on the iGPU. iGPU is enabled in bios and shows up in device manager as installed and working. I have installed the latest drivers for both GPUs.
With VP15 and Intel Pre-DCH iGPU driver (6373 - before Nov 2018) VP15 used both the iGPU and the AMD RX580 for timeline editing. For example scrubbing in the pan/crop window was fast without any lag (4K) and I could watch the usage for the iGPU go up and down as I scrubbed. QSV and AMD renders were available in the list and were faster than software renders by a good margin and I could see usage go up for the GPU being used in the renders and in fact both GPUs would be used to some extent during the render.
DCH drivers for the 630 were released in Nov and QSV stopped working with VP15. I went back to the pre-dch driver for a couple months.
MS pushed out the new April windows and forced a driver update to 6374 (still pre-DCH) but VP15 crashes after a few seconds with that driver. The new windows (1903) blocks the install of the 6373 driver!
I read some forum threads of people using VP17 successfully with both the iGPU and an AMD video card so I upgraded to 17.
VP17 sees both the AMD and Intel GPUs. They are both in the list in preferences/video GPU acceleration. In preferences/General I have enabled QSV for encoding and decoding, Use GPU for ACES Color and Enable OpenCL/GL for Intel GPU and I have set GPU acceleration to AMD in the VIDEO settings.
With VP17 and the most recent iGPU and AMD video drivers and using task manager/performance to monitor the usage during editing (scrubbing 4k video in the pan/crop window for example) the iGPU usage never moves off 0% and the AMD stays in the 0-3% range and it lags. In addition I can select a render using QSV but again the iGPU usage never goes above 0% and the render takes the same time as using software only.
Why can't VP use the iGPU?
If anybody has this working do you have a monitor attached to the iGPU? I would do that but the iGPU cannot run my 4k monitor at 60Hz over HDMI but the AMD can.