What you're seeing in Q1 is usual. The 630 silently works behind the scenes and does not appear as a separate device. This answers Q4 and Q5 too. Look at other threads (such as CaseySJ's Designare build that I referenced several times), they behave the same way: the iGPU functions in parallel with the graphics card, but is cosmetically silent.
If you want to see how your system truly behaves without the iGPU, go into BIOS and disable it. Then you'll have a system like an iMacPro, NOT like an iMac19,1 and you'll have to change the SMBIOS accordingly. (I'd not recommend doing this, unless you wish to experiment and see how things behave with different SMBIOS settings.)
I would be more concerned with
test results than
monitoring results. Monitoring results can also depend on whether you're using VirtualSMC or FakeSMC. (You might want to compare each of these methods.) If the Hackintool's settings give you better
test results, then I'd go with that method.
My original intent of this thread was to get iGPU alone functioning for a truly SFF build, which is how I use this mobo. When a graphics card is added, the iGPU goes silent in cosmetic reporting except you will see a bump in processing as it supports the graphics card (as I'd earlier addressed
here). Another test that you're familiar with is Videoproc. If the iGPU is working, then the graphics status is "Unavailable" rather than "Available" as shown below. My set-up shows "Available", so whether it is cosmetically appearing or not, the bottom-line is that it's working.
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