Chenbro NR40700 doesn't boot properly...1 sec up, 2 sec down... indefinitely


Recommended Posts

Hi All,


TLDR: Case powers up and immediately powers down. Will continue to do it until fully unplugged - wait 30 - plug in and boots on second cycle.


First, Chenbro support will not even respond; tried SIX times! This will be my only, and LAST, case from them. It is has been SuperMicro, and will continue to be forever!


Anyway, I have this Chenbro NR40700 case that I bought new (old stock) and was clearly and obviously brand new. It came with two of the custom EMAC power supplies. From day one the unit would continually power cycle (1 sec on, two off, 1sec on, two off......) and will continue to do this until I unplug the unit, wait 30 seconds, plug back in and "cycles" once and then on the 2nd try will fire up. This is completely repeatable.


I have replaced the two original power supplies and even have the thing loaded with all FOUR power supply slots filled and plugged in. I checked all of my power, etc plug in connections to the back-planes. I currently only have 14 spinners and one SSD scattered across the two back-planes. All six + two Noctua fans, dual CPU w/32 GB for each. So, nothing special.


I am down to wondering if the thing was defective from the beginning. I think I have narrowed it down to the power supply(s) distribution unit, where all the cables come out to supply power to the MB and back-plane (drives). My logic is that I have replaced the power supplies and it always starts when I unplug it and let the power drain.


I am VERY frustrated with this and would love any input/suggestions anyone has as to what to look at next. Sadly there is very little documentation on this unit to help with troubleshooting.


Thoughts anyone?


Much appreciated!!!!

Link to comment

Have you tried a different motherboard? The board is in charge of changing the power state from standby to on, the PSU only supplies minimal power to the board until one of the PSU pins is held low, so if the motherboard doesn't hold that pin low, it will power off.


You can test that theory with a cheap PSU tester that plugs into the motherboard connection, one similar to this. With the tester plugged in, the PSU's should go to full on and stay that way as long as there is AC.


(image stolen from a quick search)

Link to comment

I hope not too, as I bought it new and it worked fine in my other SM case.


One last thought, what are your thoughts about not having the SM

JPI2C1 --- Power supply SMBbus I2C header   connected.


There is no connector/plug for it coming from the power supply wire breakout module.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.