HP Z400 does not seem to flush or drain the power from graphic cards when shutting down

[testhis]

HP Z400 does not seem to flush or drain the power from graphic cards when shutting down.

When trying to power on the machine the power button flash red 4 times. I then unplug all 4 displayport cables from both Nvidea quadro 2000 cards; unplug the power; regplug the 4 displayport cable; replug the power cable and only then the machine boot into windows 7. From there all is well and fully working at full resolution for all 4 monitors

If I restart the machine, the machine restart and boot into window 7 again without any problems. But if I shutdown the machine, I need to unplug all the cables again the next time I try to power on the machine.  If I leave 1 display port pluged in one of the card the machine will boot without having to unplug anything. It boots normaly. If I leave 2 displayport cable in, on one of each card, the machine will boot normaly without having to unplug anything. The moment I connect two displayport in the same card then the machine start to flash the power button red again while beeping. So 2 display in the same cards does not boot unless I use the unplug replug process.

1 DP in each cards boot normally and don't require the unplug, plug process. 

2 DP in one of the card require unplug plug process

2 DP in each cards require the unplug, plug process.

Since everything work fine after I have unpluged replug and restarted the machine, there is no hardware problem. All monitor run all day at full resolution without any problem. The nvidea manager allowed me to configure everything and all monitors are detected and fully working.

I tested the memory slots, change the cmos battery, reset the bios, the firmware is the latest, the graphic card driver are the latest and anyway the monitor would not work after I am able to boot. etc.  I went through every possible scenario. The only thing I can think of is that the system is not automatically flushing the power left in those cards when I  shutdown. Basically, when I unplug everything I am actually making a manual flush of the power left in those card because while I unplug the 4 displayport cables and the power, I leave the other usb (mouse, flash drive) in and the system start anyway. It mean it is the displayport cable input of the card or the cable themselves who are drainning power from the board. Meaning, the system, when the DP cables are not unpluged, catch some power drainage from either the cards or the displayport cable and cannot start and flash the power button red. Once I have unplug those cable and plug them back. I am able to boot normally.

The minute their is 2 displayport in one card the system refuse to boot. These  card use only 20 watts per so the Power shoould be able to handle them it easily. I don't play game. it is for excel data mainly. These card are fully compatible with the machine and all driver are up to date and they are exatcly identical.

I also tried the cmos yellow button reset.. But I am not sure what it does exactly and in what order thing must be done..

So what I am looking for is someone who can actually tell me if the auto power flushing on shutdown can be reset or reactivated

in any way? 

It seems the computer is not doing this job entirely because some of the power stay in either the cables, the cards or both forcing the unplug replug process.

Regards

[BeemerBiker]

There is a possibility that the current supplied through the display port to the monitors exceeds the specifications and / or the ability of the system to provide the power and the system does the 4 red blink codes which indicates power problem

https://support.hp.com/us-en/document/c03599666

Discussion of display port power requirements are here

http://monitorinsider.com/displayport/dp_pin20_controversy.html

The z400 is somewhat old.  The cables that came with it may have the pin 20 problem. Do you have adapter DP to HDMI or DVI or VGA?

If the current draw through the DP exceeds .500ma the system will probably not boot.  For testing purposes you might borrow an HDMI switch that has its own power and connect one of the ports to the switch.  The switch has its own power so it does not need to draw power from the card.  If he problem disappears that is confirmation of the pin 20 problem.  This is just a guess on my part.  

I have owned 3 of them, all convert to use ATX power as the HP power was not sufficient for a pair of GTX-1070. but I suspect your graphic cards to not draw as much power.

Is there a reason you have not done the free upgrade to windows 10?

Regards