HP Z800 alternative power supply found!

Hi All,

If you’re here, it’s probably because you have a failing Z800 Power Supply. 


When the power supply starts failing it will randomly turn off, or not turn on.  With time, this problem will progressively get worse.  There is no established repair for this issue, with the only option is to buy another power supply off eBay.  …Although, the eBay power supplies are equally as old and it’s probably just a matter of time before the same fault begins.


A prior poster (another website) found an alternate power supply, but unfortunately didn’t provide any Part Numbers, documentation, or instructions for installation.  I’m presenting what I did, with instructions and pictures. 

I hope it helps future Z800 users.



WARNING / DISCLAIMER: This effort deals with electricity, wiring, soldering, modification, and careful assembly of an alternate power supply into the Z800 workstation.  All activities contained in this modification may harm you, hurt you, or worse.  This mod uses a power supply that was not designed for the Z800 workstation.  There is no guarantee of its functionality, reliability, or even its safety.  Improperly used power supplies may result in electrical shock, damage to the computer, and/or even present a fire hazard. 

This is presented as informational purposes only, with no guarantee expressed or implied.  If you follow these steps – You accept responsibly of all hazards and any intentional/unintended consequences. Proceed at YOUR own risk.


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  • To begin with, here’s some general information about the original Z800 power supply.

    The Z800 has 2 sizes of power supplies, with most people having the smaller 850-watt supply.

    The 850W power supply provides: (+12v @ 70 amps), (+5v @ 5 amps), and (-12v @ 0.15 amps).


    (See Pic1)

  • Reference the Z800 manual here:


    Search for Power Supply Specifications (Table 1-6, page 11 / pdf-page 23)


    The approximate physical size of the Z800 PS is 14” x 5” x 2” maximum (for the rectangular section).

    Therefore, any replacement will have to meet the power supply requirements, and be smaller than the original (to fit in the original location).


    The alternate Power Supply that will be used was for the Hewlett Packard ProLiant (ML350 Generation 5), (ML370 Gen 5), and/or (DL380 Gen 5) servers.  There are several different power supplies available for these servers - each with different part numbers.  I can’t verify the physical size of the other power supply part numbers, but here’s the one I used:


    HP power supply: PN 379124-001, ATSN 7001044-Y000. 

    It’s a 900-watt power supply, providing (+12v @ 72 amps), (+5v @ 2 amps), and (-12v @ 0.3 amps).

    The physical size is 8.5-9.0” (L) x 3.375” (W) x 2.06” (H).


    (See Pic 2)

  • There’s a large supply of these power supplies on eBay at reasonable prices.

    You may note, the alternate power supply is slightly taller than original (2.09” versus 2.00” original), but rest assured – it will fit.


    The old Z800 power supply (electronics) is no good, but we will re-use the case:


    1) Unplug and remove the original power supply from the Z800 workstation and let it sit for a few minutes to allow the capacitors to drain off voltage.  (See pic 3)

  • 2) Remove the top cover of the power supply. (See pic 4)

  • 3) Remove the side panel with the connectors. (See pic 5)

  • 4) Unplug the 110V plug from the board, unplug the (2) fan plugs, and remove the (1) LED light from the case.  Remove the (5) screws that mounts the board to the case - and remove board. (See pic 6)

  • 5) There’s (1) stand-off located in the middle of the case.  Grab it with some pliers and bend it until it pops off.  Use scissors and cut the top flap off - along the upper fold line.  Use pliers and bend down the flange shown in red.  (See pic 7)

  • 6) Look at the original power supply board where the wire connectors are attached.  The board is stamped with the corresponding voltage where each wire is connected.  (See pic 8)

  • 7) Each bundle of wires is crimped together with a metal band and then the band is soldered in place.  Unsolder the wires (i.e. the bands) from the circuit board.  As you unsolder the wires, attach a label to the wire bundle with the corresponding voltage. 

    The attached figure shows (wire color), (pin location), and (voltage).  (See pic 9)

    When complete, the case side panel will be completely removed from the board.  (See pic 10)

  • 8) For each connector, solder on an 18-20” extension wire to each wire bundle.  Shrink-wrap or electrical wrap each solder joint.  Label the far ends of the extension wires with the appropriate voltage.  (Or use different wire colors to indicate different voltage.)  (See pic 11)

  • Prepare the alternate Power Supply:


    9) The alternate power supply has a mechanical catch which will need to be removed.  Remove the cover and lay it over.  Use a screwdriver and pry between the catch and the cover.  Keep prying until the catch pops off.  Reassemble the cover back on the alternate power supply.  (See pic 12)

  • 10) This power supply is utilized by many different people for many different purposes.  Luckily, the hard work has already been done – which is figuring out how to wire it.  See attached links for research:


    Note: The RC group is hacking several different power supplies, so if you’re reading it – pay attention to which PS they’re talking about.  Post #958 is the important one.






    And/or search YouTube for “DPS-800 Power Supply” for more videos.  (DPS-800 is a similar PS)


  • 11) For the purposes for the Z800, use the attached wiring figure.  We will connect the blue wire and the red wire to turn the PS on.  We will use the (+12v / +5v / Ground / -12v) pins for the Z800 connections, which are circled in thick green boxes.  (See Pic 13)

  • 12) Use a piece of wire and solder pin 31 to pin 34 (see blue line).  Connecting pin 31 and pin 34 turns the power supply on.  Disconnecting the pins will turn the power supply off.

    Note: You will see from the pictures that I hard-wired the power supply ‘ON’ without a switch.  I’ll explain further at the end.


    13) Use a piece of wire and solder pin 30 to pin 1 (+12v).  Per the RCgroup discussion, connecting pin 30 and pin 1 allows the power supply to better regulate the +12v output.

    After attaching the (2) wires, it should look like (pic 14).

  • 14) Now we begin to start soldering on the Z800 connector wires.  We will be using the wiring figure and start soldering the extension wires to the indicated locations (+12v, +5V, Ground, -12V).  Be sure to solder the wires to the correct contacts.   

    Trim wires to fit, and be sure none of the wires (or attached labels) interfere with the Z800 factory fans.  When complete it should look like (pic 15).

    Note: (PS-ON) IS NOT USED.  I did not use the (PS-ON) wire for the alternate power supply.  I covered the wire end, and left it as-is and not connected to anything.  More about this discussed below.

  • 15) Take an old computer power cord, cut off the female end – and solder it on the Z800 original case 110V plug wires.  This gives you an easy way to plug the 110v receptacle into the alternate power supply.  There is a small electrical standoff near the 110v plug location.  I used the electrical stand-off for my grounding location. (See pic 16)

  • 16) Rotate the alternate power supply to nest inside the Z800 power supply case.  Nest all the extension wires nicely under the connectors wire bundles for a cleaner look.  Insert the 110V plug into the alternate power supply.  Use a zip-tie and connect the alternate PS handle to the back of the Z800 case.  The handle will not be flush with the case – but the zip tie will keep the power supply snug in place so it doesn’t move.  (See pic 16 and pic 17).

  • 17) Reattach the back connector panel to the case (3 screws).  Discard the original top panel, as we will not be re-using it.


    18) Insert the alternate power supply into the Z800.  It will be a bit tight sliding it in, but not too bad.

    (See pic 18)

  • ALL FINISHED!!!  The alternate power supply is ready to power your computer.  This alternate power supply should last well until the Z800 Workstation is fully obsolete and no longer worth repairing.

    I hope this has been helpful.



    In the instructions (step 12) - I attached a solid wire connecting power supply (pin 31 and pin 34).  This forces the alternate power supply to be ‘ON’ anytime 110V is connected.  When I’m not using the computer - I use an external power strip to remove power from the power supply / computer.


    Optional: If you choose, you can utilize the Z800 (PS-ON) pin to activate a relay to connect/disconnect pin 31 and pin 34 for ON/OFF respectively.  The motherboard supplies pin (PS-ON) with +5V for standby, and 0V for ‘ON’.  I opted not to use a relay, and instead, I hard-wired the PS to always be ‘ON’. 


    If you also hard-wire the power supply, here’s the computer startup process that I have:

    1) Turn on the external power strip which provides power to the PS.  When power is applied - the (PS fans) and (computer CPU fans) will turn on full blast (loud) - even though the ‘computer’ is still off. 

    2) Turn on the computer via the front face ‘ON’ button.  The computer will start up as normal – and once the CPU fans receive signal from the computer, the CPU fans will throttle down to normal fan speed.  The computer is now on - use the computer as normal.

    3) When finished with the computer, shut-down as per typical computer process.  Once the computer has completed the shut-down process, turn off the power strip.

    4) Repeat as needed.



    The alternate power supply has its own cooling fans incorporated, which works fine. 

    Although, if you want additional cooling for the alternate power supply, you can wire up the original cooling fans.  The original fans are (4) wire fans: Red (+12v), Black (Ground), White, and Blue.  The white and blue wires are for fan speed control – which we can’t use now.

    If you connect only the Red and Black wires to the power supply, the fans will turn on full blast, which was too loud for me.  A simple work-around to slow down the fans is to incorporate a (10 watt / 10-ohm) resistor in the power wire going to both the fans.  The resistor will drop the available voltage for the fans to about 8.5 volts – which is a decent medium speed. 

    WARNING:  The resistor must be a 10-watt resistor.  The original fans are 12-volt x 0.26 amps, which is about 3.12 watts per fan, or for both fans is 6.24 watts.  If using 1 resistor to slow both fans, the resistor wattage must exceed the fan total wattage.  Therefore, the resistor must be a 10-watt resistor for safety purposes.  Do NOT undersize the resistor wattage.  (Search eBay for ‘10watt 10ohm resistor’)

    A (10 ohm / 10-watt) resistor is about right for a medium fan speed.


    I opted not to use the original fans (for now at least).  Mainly because the alternate power supply fans are sufficient for its cooling.  Over extended computer usage – the exhaust airflow may get warm.  If it gets warmer then you like - adding the resistors for the extra fan cooling can always be added later.

  • For all the instructions and pictures in (1) file, here's a complete PDF of the steps.

  • If your curious of the original user that found the alternate power supply, do an internet search using the title of this thread.

  • Nothing Relevent to Add i saw this on Linus tech tips forum.  Thanks for sharing.

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