Dead z420?

[Kim4863]

Hello. 

For some reason my hp z420 wont power on at all. I remove the mbo and placed in on a box to test with the psu, when i plug both motherboard power and cpu power nothing happens all but when the cpu power is plugged in the cpu fan starts spinningen and psu seem to be working with lights and fan rpm.

Thanks

[Brian1965]

Hi Kim4863,

The HP Z workstation PSU's have a built in self-test (BIST) as detailed in the HP Z420 Maintenance and Service Guide. You can find various Z420 resources here; HP Z420 Support Page 

Specifically;

[Ulf_K]

Here is another strange but fortunately only-once problem: I fired up a newly acquired Z420 V2 after just replacing the mech hard disk with an SSD in order to reinstall the O/S.  What happened was that the fans ran at maximum speed, no video output.

The system remained in that state and the next stage where the fans that normally slows down a few seconds after power-on following the POST/BIOS start screen never ocurred.  Powering OFF/removing AC power and clearing the CMOS did not help either. Eventually, I reseated the CPU and the memory sticks (that had not been tampered with). After some more attempts, the system came back to life.

Since this problem is not mentioned in the Troubleshooting guides (no video, no "Beeps", no RED LED light, etc) it would be interesting to hear any suggestions what this problem might have been...

[Kim4863]

Hey. Thx for replying.

When i put the motherboard power in full way its like its dead and no power at all, not even a single light. And when i unplug motherboard power and only 8pin cpu is left the cpu fan spins. And last when i put motherboard pin in half way and cpu pin all the way the fans spin to 100% but no display 

[Brian1965]

Did you test the PSU (by itself) as per my last post;

CAUTION: Plugging in the motherboard power connectors (or any internal components, cards, etc.), with the PSU powered on, can damage the PSU, motherboard, CPU, etc. This should NEVER be done! Always remove AC power (switch off) before plugging or unplugging peripherals or cables. The ony exception is external peripherals, e.g. USB, thunderbolt devices, etc.

[Kim4863]

Hey, The psu works 

Is it the board? 

[Brian1965]

Possibly, but before writing off the motherboard . . .

1)  If you haven't done so already, I would recommend you try  removing and re-seating the CPU and heatsink. It is also a good opportunity to inspect the CPU, and the motherboard CPU socket for bent or damaged pins.

2)  Replace the motherboard CMOS battery (CR2032). Under normal use, the motherboard CMOS battery life expectancy is about 5 years. If you don't know the history of the system, (i.e. purchased secondhand/used?), then the CMOS battery may be completely dead.  - Since the battery is cheap, it certainly wouldn't do any harm to replace it.

3) You could also try performing a BIOS Crisis Recovery. There is an excellent and very detailed post by fellow forum member SDH on how to perform this procedure. This should be done with minimal hardware installed, e.g. CPU, RAM, GPU and OS drive only.

If none of the above work then I suspect the motherboard is damaged.

[Kim4863]

Thanks. I will get back to you when i have tried this.