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Cisco C240 M4 - DC Output Not Enabled

Hello all, I have scoured the planet and have found absolutely nothing on this topic.

What does it mean when the server power supplies, PSU, both of them, blink their green lights?

According to the service and install document, it means power AC or DC is ok, but DC Output Not Enabled.  (Mine are AC PSU if you need to know).

Also in another part of the document, when the fault LED is off and the status LED is green blinking, it says the 12v main off and either standby power mode or CR slave PSU is in sleep mode.

The above details can be found in the document titled:

Cisco UCS C240 M4 Server
Installation and Service Guide
May 06, 2015

Here is what is happening in the best I can describe:

Connect one or both power cords

Status lights (green ones) both begin to simply flash in a simple on/off pattern and doesn't stop or change.  Observed over many hours.

Front panel LEDs shows the power button is Amber

When pressed the server attempts to power on and than very quickly it powers off again... <1sec

I can hear the fans attempt to start and see green illumination from inside the chassis briefly turn on and off again as well

Eventually, the front panel LEDs might show amber (system off/standby) for power button, and green for all but the network LED.  Maybe this is a code of some sort.  I have found nothing about this anywhere.

Server doesn't power on, however i can confirm the IMC is running, I can reach it over IP but cannot login.  Not sure if there is a problem with the password needing to be reset or perform recovery procedures, which I also would need some help with, seeing as the only factory reset or similar things i have found say i need to log into the IMC to perform.  sigh.

Much obliged fellow Cisco pros.


Re: Cisco C240 M4 - DC Output Not Enabled

Did you ever figure out what the problem was? We have the exact same behavior.

Cisco Employee

Re: Cisco C240 M4 - DC Output Not Enabled

Hello everyone!


I have a problem with my UCS c240 M4. After I upgrade the memory on my server, it didn't detect the power cord connected to the power supplies. I also change my power cords and power supplies but it's still the same. Please let me know if any has the same issue. Thanks! 

Cisco Employee

Re: Cisco C240 M4 - DC Output Not Enabled

Can you confirm what kind of PSUs you have installed?

There are some 1400W PSUs that are 220V only


If Power is confirmed to not be an issue, then you may want to check seating on CPUs, DIMMs, reseat PSUs, any adapters/PCI-E cards.


Try plugging a known DHCP enabled network up to one of the 1Gb LOM ports, and then check your DHCP server to see if the CIMC grabbed an IP address.  If you can get the CIMC functional without having to get through POST (which is where you can manually setup CIMC/F8) that might help you with diagnostics as the server only needs power to the PSUs and server doesn't have to be powered on for CIMC to work.

Alternatively use something like tftpd32 that will supply DHCP address response via a notebook and cable directly hooked to 1Gb LOM ports, and see if you get an IP consumed.

If you do, then use username: admin, and password of password



Cisco Employee

Re: Cisco C240 M4 - DC Output Not Enabled


My server came back online after I shut it down for a couple of hours and I don't have any more issue on power. I think there is something wrong with this server probably on the motherboard. Thanks though!




Cisco Employee

Re: Cisco C240 M4 - DC Output Not Enabled

I would make sure you configure the CIMC via F8, that way you can get diagnostic info, which will be required if you decide to open a TAC case.

It is highly unlikely that your server would not power on without something being logged as to the reason.




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