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HP Recommended
hp z420
Microsoft Windows 10 (64-bit)

My HP z420 stopped working.

It was working. I was trying to install Windows-10 off a NEW USB thumb drive and then it just stopped working.

It powers on with blue button light on but that is all.

will not posts.

I removed the battery and hit the reset button on the motherboard but same results.

I power cycled and tried unplugging and pushing the power button to clear the PSU of voltage.

But still will not posts.


Can someone tell me the correct way to reset the motherboard ?


or how to fix the problem with it NOT posting ?

Alex Hernandez
HP Recommended



If the power light is on and a steady blue, just to eliminate it as a possibility:


1.  Verify the monitor is properly connected.

2.  If you have another known working GPU, try swapping that in.

3.  If possible, consider testing both the monitor and GPU in another system. 







HP Recommended

Well, I tried swapping out the GPU for another one and I tried both GPU slots with NO success.

The monitor is actually a 24" TV with HDMI port.

The TV works and the HDMI port is working it reads " No HDMI signal"

because the computer is not providing an HDMI signal.


Do you think the problem is the motherboard or PSU ?


The computer will NOT display anything, Blank screen with NO signal output. GPU is Good.

Computer will NOT posts.

I tried both GPU slots.


Is there a way to reset the motherboard ?


Alex Hernandez
HP Recommended



In the absence of any display, error messages and/or power button error codes, there is little data on which to base a repair response.




1.  Remove CMOS battery and after 24 hours, replace it with a new one.


2.  Before restarting, remove all peripherals, and all drives except the one containing the C: partition.


3. Remove and reseat the GPU


4. Remove and reseat the main PSU to motherboard connection


5. Restart


6.  If the result is the same as previously, with the steady power light, the fault is probably is not the PSU and may well be a motherboard failure. The conditions would be different if the fault is a corrupted BIOS.


I hope others will comment, but at some level, the loss of system use time- apparently several day already, and the uncertainty/ frustration may be solved with a motherboard replacement.  Currently, in the US, it appears that a z420 v2 (2013 Boot Block Date) is  perhaps an $70- $90 purchase. 


The chassis design makes the motherboard replacement tool-less and quite fast: 


1. Unplug all chassis , GPU, LAN, USB, drives & etc. to motherboard connections

2. Remove the CPU and memory fan shroud /cover

3. Rotate the standing green retention tabs on the chassis.

4. Slide the motherboard towards the front of the case until the motherboard holdoffs reach the front of their slots

5. Tilt the motherboard and remove from the case.

6.  Withdraw the motherboard from the case


Replacement is the reverse of the above. 


As mentioned, I hope others will comment. Let us know what happens. 




HP z620_2 (2017) (R7) > Xeon E5-1680 v2 (8C@ 4.3GHz) / z420 Liquid Cooling / 64GB (HP/Samsung 8X 8GB DDR3-1866 ECC registered) / Quadro P2000 5GB _ GTX 1070 Ti 8GB / HP Z Turbo Drive M.2 256GB AHCI + Samsung 970 EVO M.2 NVMe 500GB + HGST 7K6000 4TB + HP/HGST Enterprise 6TB / Focusrite Scarlett 2i4 sound interface + 2X Mackie MR824 / 825W PSU / Windows 7 Prof.’l 64-bit (HP OEM) > 2X Dell Ultrasharp U2715H (2560 X 1440)

[ Passmark Rating = 6280 / CPU rating = 17178 / 2D = 819 / 3D= 12629 / Mem = 3002 / Disk = 13751 / Single Thread Mark = 2368 [10.23.18]

HP z420_3: (2015) (R11) Xeon E5-1650 v2 (6C@ 4.3GHz) / z420 Liquid cooling / 64GB (HP/Samsung 8X 8GB DDR3-1866 ECC registered) / NVIDIA GeForce GTX 1060 6GB/ Samsung 860 EVO 500GB + HGST 4TB / ASUS Essence STX + Logitech z2300 2.1 / 600W PSU > Windows 7 Professional 64-bit (HP OEM ) > Samsung 40" 4K

[Passmark System Rating: = 5644 / CPU = 15293 / 2D = 847 / 3D = 10953 / Mem = 2997 Disk = 4858 /Single Thread Mark = 2384 [6.27.19]


HP ZBook 17 G2: (2015 ) i7-4940MX Extreme (4C@3.1/ 4.0GHz) / 32GB / Quadro K3100M 4GB / Kingston 480GB SATA SSD > 17.3" LCD 1920 X1080 panel > HP docking station> HP 2711x 27" LCD + Dell 17" (2007!) / Logitech 533 _2.1 speaker system

[Passmark System Rating: = 3980 / CPU = 10140 / 2D = 618 / 3D = 2779 / Mem = 2559 Disk = 4662 / Single Thread Mark = 2387 [1.3.20]


Network: Netgear GS108-400NAS


† The opinions expressed above are the personal opinions of the authors, not of HP. By using this site, you accept the <a href="https://www8.hp.com/us/en/terms-of-use.html" class="udrlinesmall">Terms of Use</a> and <a href="/t5/custom/page/page-id/hp.rulespage" class="udrlinesmall"> Rules of Participation</a>.