Multiple monitors, Desktop, possibly intel HD graphics

I have a trouble with multiple monitor configuration with GTX970, linux. It worked with old intel Corei7, but not with Core i7 integrated graphics. (integrated graphics is not used)

OK
DVI-D -DFP
DVI-I -DFP
Display Port -DFP
HDMI -DFP

OK (any three monitors OK)
DVI-D -DFP
DVI-I -CRT
Display Port -DFP
HDMI - NC

Don’t work with i7 HD, OK with i7 (old)
All monitors are blanked when starting X.
DVI-D -DFP
DVI-I -CRT
Display Port -DFP
HDMI - DFP

After booting with 3 monitors configuration, rest one can be recognized from nvidia-setting.

I could not find way to disable onboard graphics in BIOS setting.
The monitors are numbered like (CRT-0, DFP-1, DFP-4, DFP-5) with intel HD CPU,
and (CRT-0, DFP-1, DFP-2, DFP-3) without HD.

I would appreciate any hints to solve the problem.