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HP Z800 ATX Power good signal to external power supply unit?

Started by Prettypicturegirl, February 11, 2018, 06:44:18 am

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Hi Andy,

maybe you can point a "non techy" in the right direction? I'd really appreciate it.

I have an HP Z800 of which I want to upgrade the graphics card to one, or possibly later two, GTX 1080Ti or GTX1080.
The cards draw 250watt each and require two 8pin power connectors each. Clearly to much for the 850watt psu inside the machine.

I was thinking of upgrading to HP's internal 1250watt psu, but it has a number of drawbacks.
-very expensive 503€
-Not enough & not the right connectors
-Not a good reputation in terms of reliability
-More heat builtup inside the machine
+Lives inside the box

So I plan to add an external 600watt ATX power supply for the graphics cards. The rest (motherboard & Co) will continue to run over the internal HP psu.

+Enough reliable power (2x 300watt)
+Correct number and correct type of power connectors (4x 8Pin)
+65€ only
-External box (it "lives" under the table so i do not mind at all.).
-Needs ATX "power good signal to work"

Here is my question.
I need to branch off the "power good" signal to sent it to the ATX connector of the external psu.
All adapters I have seen so far only allow either an ATX Y or plug into the HP power supply connector which would than be occupied by it. Still, I need this plug to be fully functionally attached to the motherboard.

Can you tell me please, if I could connect the two "power good" pins of the ATX (14 green & 15 black) on the external PSU to two pins on the memory power supply cable of the Z800?
Which two pins on the HP cable should/could I use in this case?
I think the easiest would be to simply solder two cables to the HP cable and attach them to an ATX connector which plugs into the external psu.

Once this ATX connection is made I would connect the two cards to the external PSU and leave the external psu in standby.
When the Z800 gets switched on, the "power good" signal goes to the external psu, switches it on and supplies power to the two graphic cards.
Would that work?

Last question.
Do you think the 850Watt HP internal PSU would have enough power for a processor upgrade from dual X5650 to dual X5690 remaining if the graphics cards are  not attached to it?
I have the dual X5650 version right now. Do i need to upgrade cooling then?

Thanks so much,



Thank you Very much.

However I had a spare Supply.

Maybe I should say a supply that was not in use, it was purchased for my 3DP11 that had never installed.
My first 3DP11 is working perfectly well with the Original power supply a 12v 30a 360wt.

Though I do appreciate the offer.