I have been playing around with triple monitors before my SSD arrive (and reinstall and provide IORegs after)
Skylake Dell E5470 HD 530 (0x191b0000) laptop (2xDVI on eDock), can drive 3 independent displays on windows(laptop screen + 2xDVI on eDock)
In OS X, I can boot laptop screen + first DVI (port 6) with no issue. If I try to connect second DVI (port 5), the laptop screen goes blank (and no way to wake it up other than reboot), can see both DVI monitors. OS X display manager reports all 3 screens are connected
If I try to boot laptop screen + second DVI only (port 5), unstable results (sometimes works, sometimes graphics glitches). Looks like second DVI port(port 5) is unstable, needs some investigation. tried combination of the different fixes available (4-port patch, port5 and/or port6 patches), no improvements