I have an HP EliteBook 8470p w/ Intel 3320M and HD4000 graphics on an HP docking station. I am trying to run 3 displays (on board display and 2 external monitors). I read through the FAQ and I'm trying to do my best to set this up but it isn't working.
Now I will start this by saying my 2 neighbors here at work do have 3 displays working. They are using HP EliteBook Folio 9470M with Intel 3437u and HD4000 graphics on an HP slim docking station. They have an active DP to VGA adapter to 1 monitor, VGA connected directly to the back of the docking station for monitor 2 and the on board display. I borrowed the adapter and tried this same setup but no dice. The PC detects all 3 monitors but i cant enable more than 2 at a time. I've tried using the vga and dp connection on the docking station, the vga and dp port on the laptop itself, and any mix there of I could think of. I'm not sure why it wont work for me. I know it's a different model laptop and docking station, but we have the same HD 4000 chipset, same drivers, same OS (Win7 Enterprise 64), same monitors, same cables and same adapter.
I am sorry you are having this problem but let me help you.
Please note that In order to have triple display configuration is important to have a special configuration. Check below:
It is very important to say that using adapters (active or passive) may interfere on the signal and cause problems when trying to get the configuration.
Here you can check very important information about the 3 displays configuration: