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HP Recommended



I have Z820 with one 2690 Xeon CPU. It ran into cyclic reboot with no POST or any beeps.

1. I've just shutdown it few days ago.

2. Then I've turned it on next day. It turned on - no POST screen, no beeps, fans at normal speed, blue power light. Then it shut down after a while, stayed off for 5 seconds and then turned itself on again with the same result (goining to reboot after a while).


I've tried:

- disconnecting and reconnecting power cord

- clearing cmos

- removing the battery

- disconnecting all the drives

- removing all memory modules except one in the DIMM1

- rotating memory modules in DIMM1

- rotating all of the memory modules

- removing the GPU

- removing all of the memory modules


All the same. Cyclic reboot:

- about 25 seconds after power on with no POST or any beeps, blue power light;

- kinda "auto shutdown"

- 5 seconds stays off

- automatically powers on;


Well, I've tried entering Crisis Recovery with JP15, but no luck with two different flash drives and with DVD with bin file. I cant' even get red light and beeps. JP15 is in 2-3 position, but power light is still blue and no beeps.


I don't know should I enter Crisis recovery in this case or not, I've just tried it. May be this is another kind of problem.


So main question is: does cyclic reboot looks like something I can deal with BIOS and crisis recovery with? Or is it another kind of problem?


P.S. I've tried entering crisis recovery with various hardware combinations and with nearly no additional hardware, and with different formatting options for flash drives.

HP Recommended

Have you tried testing the PSU via the BIST (Built-In-Self-Test):-


To check the power supply functionality.
a. Disconnect the AC power.
b. HP Z820 Workstation only — Remove the power supply from the chassis. All other workstations, unplug cables connected to system board.
c. Plug in AC power.
● If the power supply fan spins and the BIST LED illuminates, the power supply is good.
● If the power supply fan does not spin or the BIST LED does not illuminate, replace the power supply.


NOTE: The LED might only be visible from the rear of the PSU.




HP Z620 - Liquid Cooled E5-1680v2 @4.7GHz / 64GB Hynix PC3-14900R 1866MHz / GTX1080Ti FE 11GB / Quadro P2000 5GB / Samsung 256GB PCIe M.2 256GB AHCI / Passmark 9.0 Rating = 7147 / CPU 17461 / 2D 1019 / 3D 14464 / Mem 3153 / Disk 15451 / Single Threaded 2551
HP Recommended

Hi. Thank you for the suggestion. I've detached the PSU, plugged in the power cord: fans are running slightly, LED is green. So it seems to be okay, isn't it?

HP Recommended

is this a ver 1 or a ver 2 motherboard? v1 boards are sandy bridge only, although some v1 boards have been able to run a single v2 cpu most have some issues doing so


if you are running a v2 cpu in a rev1 board, try replacing the cpu with a cheap test (sandy bridge) cpu


i've had 2 systems that failed with the same symptoms you describe, due to time restraints we never spent a lot of time on either board, but our rather limited testing indicated a board failure rather than a corrupted bios  


not what you want to hear i'm sure


if you do look for a replacement board, don't overlook a bare bones system as sometimes the pricing on them works out better than just a board as you get many spare parts!!


and last, make sure you get a board with the later bootblock date 03/06/2013 which supports the v2 (ivy bridge) cpu's


board revision numbers 1.x to 1.03 are not indicative of a v1/v2 motherboard, however there was a rev 1.04 board that saw limited release late in the z820 life cycle which appears to always be a v2 board

HP Recommended

I'll try another CPU in a few days. But current Xeon E5-2690 is also Sandy bridge one. So... this looks more like faulty motherboard, yep?

HP Recommended

If you're not able to get the system to boot into Crisis Recovery mode, then I would assume at this point based on your troubleshooting steps that the motherboard has likely failed -- possibly the CPU, but that seems less likely. 


The original board that came in the Z420 (v2) I currently have failed last year in a somewhat similar fashion, although it would ramp the fans up full speed for ~5-10 seconds and then power off but not in a loop, however like yours there were no red lights indicating an issue. The first few times this happened I was able to get into Crisis Recovery and reflash it back to life but it eventually died.

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