Mac Pro does not wakeup 1 of 3 connected monitors: Philips times out

Hi,

(Setup)

I use a Mac Pro from 2014 (End 2013, AMD Firepro, D700 Graphics, 6core, 1TB SSD, 32MB, actual OSX Yosemite 10.10.2).

Connected are three monitors:

Philips BDM 4065 UC (40 great inches) via mini DP to DP cable

2x Dell 2410 (vertical/pivot to the sides of the 40" screen)

(Problem)

The setup is a dream for me, with one glitch:

when the Mac goes to sleep, all monitors nicely sleep with it. Waking the Mac up again, brings the Mac up and the Dells but not the Philips. It tries to get up (a bit of backlight to be seen), then shows a message that it goes to sleep again.

(Troubleshooting so far)

I experimented with it:

- power cycling the monitor brings it back into business

- pulling the DP cable temporarily does the job too ... sometimes

(Assumed root-cause)

Today I believe I found the reason:

In a forum sb. complained that the Philips takes long to wake up. Ok! The Dells that work are back ... instantly.

I tried this: wakeup, wait two seconds, put the Mac to sleep (mouse into active corner) and wake it up immediately.

The description sound a bit like "dance around the tree three times at full moon", but it works. What I believe that happens:

Fail:

- the Mac wakes up

- the Dells are awake instantly

- the Philips slowly wakes up

- the Mac gets impatient about the Philips and times out waiting for the monitor, stopping the signal supply

- the Philips falls back into sleep (and displays this as a message)

Workaround:

- the Mac wakes up, Dells wake up

- waste two seconds, while the Philips is still trying to wake up

- hammer the Mac back into sleep, and wake it up again

- the Philips is so slow it doesn't even notice this "brutal shaking" of the Macs wake-state

- the activite resets the wake-up-timeout of the Mac giving the Philips effectively enough time to report "ready" before even the second wake-up times out.

- et voila: a fully awake set of monitor

Now the big question:

I this timeout that the Mac on wake-up waits for a Monitor to become ready a configurable item? Can I extend this period by a few seconds to get my dream setup actually working? I fear I won't be able to make Philips solve the long wake-up time, so I check on the Apple side.

Thanks in advance.