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‎11-20-2021 01:02 PM

HP Recommended
Product: Z420
Operating System: Microsoft Windows 10 (64-bit)

**Help Requested Please

Z420  E5-2680, 32 GB DDR3, QUADRO2000 1GB GPU

Suddenly yesterday morning upon pressing power switch blue LED power button lights for 1 second then machine stops booting, like power is removed

Initially thought power switch or PS was bad.

Tested all active power pins on 18-pin MB connector with DVM.  All +12v and -12v rails are good but no +5V on pin 1 or 9 and no +11v on pin 17.  Almost forgot that HP does PSs THEIR way and has regulators on MB generate all aux(non 12V) voltages.

Removed ALL PS cables from MB, drives, but PS green LED lights up AND fan runs.  Inspected

power switch and no opens found.

Machine 6 yrs or more old so I replaced CMOS battery.  Machine tried boot but suddenly Win 10 gave message during boot that appeared to state that CMOS values were reset to defaults and  tried to finish booting but could not load Win 10 properly after 3 attempts to Self repair failed

OK.  I reset Windows 10 and all appeared to be fine and Machine performed normally for about 2 hours while I reloaded most of my apps.  

Went to start up the PC this AM and just like yesterday morning, power button lights for a second then shuts off/ stops booting completely!  At this point I'm thinking perhaps the voltage regulators on the motherboard may have failed??  Help!

 

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