HP Z400 not turning on..

[Ateeb__]

Hello Everyone,

As the title suggests my hp z400 is not TURNING ON for even a second. When i press the power
button, only the GREEN HDD LED turns on for a second or less and then it SHUTS DOWN again.
And there is also no POST BEEP or any ERROR CODE BEEPS.

Things i have already tried, btw i only have a single RAM stick inserted right now and everything else removed.

1) Tried removing everything including GPU, HDDs, SSD , RAMs.
2) Tried resetting the BIOS using BIOS switch.
3) Tried changing the PSU, with no success.

The only thing left i think, is TURNING ON the PC by shorting the pins on board, plz guide me on how to do it on HP Z400,
as the FRONT POWER button might be the issue.

Any other suggestions are highly appreciated as well.

Thanks.
 

[DGroves]

are you using the z400 power supply? if not that's your problem as the z400 does not use a standard ATX pinout

to us a ATX supply, you can buy a adapter off amazon/newegg/ebay

if using the z400 supply, you either have a bad supply or bad motherboard.

google z400 power supply test to see how to check the HP supply

[Ateeb__]

I was using a ThermalTake 700W powersupply, but i have also tried using standard HP powersupply that came with the system i.e. 475Watts PSU ( made by DELTA ELECTRONICS )..

[Ateeb__]

I have used both PSUs but non of them worked, so all these symptoms leads to bad motherboard, i guess, is there anything else left, before declaring motherboard dead?

[DGroves · Accepted solution]

yes the board appears to be dead if the HP suppply passes it's diag test

the thermaltake supply may have damaged the board depending on how long and how many times you powered the system board with it

the above is not something you want to hear, but use it as a learing experence and in the future allways check workstation/server, or oddball systems like All In One (AIO) specs before deciding at random it uses standard parts

many people only see generic systems and have no idea that non standard systems still exist, i have been in the "IT" field over 25 years and as such remember the early days when there were multiple ways of doing computer equipment

[Ateeb__]

I appreciated your suggestions,

but i cant understand how ThermalTake PSU could damage the board, i modded the PSU to make it suitable for the motherboard?

Thanks,

[SDH]

....one never knows with such mods.

The power supply is one thing I never mess with unless it is putting in the higher powered one from HP.  I have no problem with putting in used HP ones from eBay.  It is so rare that one will go bad.  But only HP ones for me...... lower or higher powered ones but HP for that workstation in all cases.

Has worked for me, and I have heard quite a few tales of fried HP motherboards from people doing power supply mods.

[DGroves]

you may have miswired the thermaltake supply, i strongly recomend you spend the 20.00 or less to get a adapter that is known to work and will be wired right

https://www.moddiy.com/products/ATX-to-HP-Z400-24%252dPin-Non%252dStandard-ATX-Pinout-Main-Power-Ada...

[Ateeb__]

btw, to test the PSU you mean to short the pins of 24pin connector? or is it something else?

[SDH]

Read up on BIST.... HP power supplies can be plugged in with nothing else attached and their green LED light will come on if it is a good power supply.  This usually points to the motherboard if the workstation is dead and the LED light comes on (meaning it passed its internal self test).

This of course has no role if you are using a non-HP power supply.  You could prove your original HP power supply works, however, this way.