1. Turns on when you connect power. You do not need to press the power button. It just turns on.
2. CPU, GPU, and PSU fans all spin. PSU will start to spin aggressively if left on for a while. (I don't remember if the memory fans spin; I took that assembly out so I could see).
3. No video output. Can't try onboard graphics because it has a Xeon CPU. So no iGPU.
4. No beep codes, blink codes, or other errors.

I would specifically like to know if the PSU is at fault (it's my current theory). Problem being. it's a proprietary power supply.

So. How do I test it? I am probably going to take the housing off and just look. But NOT TOUCH anything because I don't have a death wish. But I'm invested. And this is taking up residence in my brain.

PSU in Question. Specs/model number and weirdo connectors.

I'll probably cave and buy a new one, but I would rather be sure before I invest $$.

Stuff I have already tried. In case someone has other ideas that aren't Power Supply.

• Parsing down to minimum config (Only CPU, one stick of RAM)
• BIOS recovery
• Installing a known good GPU
• Remounting the CPU
• Swapping RAM sticks around (It has 8 slots. 3 were populated. I verified they were in the correct layout and tried various sticks in the Number 1 slot.

UPDATE 04.20.2024 - Somehow this thread keeps finding people and I have still not fixed this or found a definitive answer to my question, but hopefully these voltages will help someone, or at least contribute to this discussion. I should add, I do not believe these voltages are correct.

Measured voltages on my connector when both connectors are attached to the board and power on is attempted.

Colors are constent with typical markings

• Orange = 3.3V
• Red = 5V
• Yellow = 12V
• Black = Ground or Voltage measured
• Purple = 1V (I am not convinced this is normal, but nevertheless have nothing specific to compare to).

Even though my device powers on almost immediately after the PSU is connected to power, I can power off. Voltages with the power off.

Anything not marked has no voltage and all previously 12V lines have very nominal voltage (~.08V).

I am again starting to think the PSU is to blame. I have checked the board pretty thoroughly previously for shorts, but since it is a rather large board, this is somewhat difficult.

⟐ Answered March 03, 2026 at 6:06 MST

⟐ Answer edited September 30, 2024 at 12:59 MST

My English is bad, I read with a translator and perhaps some text is distorted for me. But the general essence is clear to me, very interesting and important.

It seems to me that I was very lucky that I found this discussion)))

I have a new Z4 G4 + core i7 7800x board, and a great desire to use it outside the original HP case, with an ATX power supply.

I know this is possible because it was done on examples of earlier Z440 boards. And there are special adapters 24 pin to 18. But unfortunately this option is not suitable for the Z4 G4.

The MB power pinout is really an HP secret and cannot be found on the Internet....

In general, the lack of a clear connection diagram for all peripherals also confuses me. Can anyone take some photos of the front panel connections on the motherboard?

I also look forward to your success in finding the true power pinout of the board.

⟐ Commented May 17, 2024 at 4:48 MST

I have diagnosed it as the power supply being the issue as it no longer works or turns back on.

I would like to keep this station and only replace the actual power supply but have no reliable sites of knowledge. I was wondering if anyone else has had this issue and how to go about it?

Model number: D15-1K0P1A

⟐ Edited by author January 15, 2024 at 1:38 MST