Quick update to say that 10.12.4 resolves the long-standing issues with the 530 iGPU on this board, at least on a single monitor. I'll do some more testing on dual monitors and report back.
On my 10.12.3 using the 530 for dual monitors (using the work-around of booting up with a single monitor and turning on the second at the desktop) with patches for the 530 (inject intel, 4 port patch, ig-platform-id 0x19120000, rename IGPU, and the Sierra "glitch" fixes), I applied the combo update, DISABLED all those fixes in my config.plist (removed the ig-platform-id and unchecked inject intel), rebooted, and everything is working as before.
I'll do some more testing on dual monitors and report back. The dual monitor fix required identifying which port was which connector using IORegistryExplorer and adding patches to config.plist. I had those in and also disabled those prior to reboot. Dual monitors on some SMBIOSes also requires the ADGPFix be applied. I am using iMac14,2 on this build for compatibility, which I believe does not require AGDPFix.
Update: dual monitors work as before. I boot up with the dvi monitor plugged in, and turn on the HDMI monitor at the desktop, and with a scientifically negligible sample size of one boot, I have dual monitors working. This is with the GFX to IGPU rename DISABLED and the port-connector patches DISABLED. Note that my Apple Cinema Display (the crystal display that used the proprietary ADC connector which I connected to DVI using the Apple ADC-to-DVI adapter) which used to support a dual monitor config on el cap and which works fine as a single monitor, does not seem to like being used in a dual monitor config on Sierra. I have a ViewSonic monitor on the DVI port now. I had dual monitors working once on the ACD but set the primary display in system prefs to my HDMI monitor by dragging the menu bar and it's never worked since. Sad.
