C - usually means  CPU Error  ---> at least on other MB
 
Check your power connections to the MB  8-pin EPS Connector



 

System does not POST, and POST code indicator reads “C” ........................................... -138 -
 
https://www.evga.com/supp.../files/142-SX-E297.pdf
 
excerpt  Manual page 138

If you power on the board and it goes directly to “C,” and nothing else, that is an indication of a CPU-related issue. It is not likely a

faulty CPU, although it is possible; instead, it is mostlikely a CPU power issue.
 

Hi thanks for the answer from both.
The problem is not the 8pin eps both are connected and there is more then enough power.
If this where the case high load or even stable use would not be possible.
I also verified with a thermal camera that both 8 pins eps cable show a slow increase in temperature. From room temp to at full load +15degrees (celsius).
 
But i will clarify.
When i come home from work and turn on main power.
Then press the power on it works normal.
You get the 4/5 happy beeps.
After 5 seconds the temperature is shown in the LED.
In 20/25 seconds my system is fully booted into windows.
if i use prime95 full load for 15 minutes as example the system still responds to any other actions even other apps start with no lag.
 
Turning off the pc and pressing power again also works normal.
It is only when i turn off and leave it off with main power to the supply it after 1,5 minute it automatically starts up to the c code.
 
 
 

Is there something weird going on with a wake on LAN or wake via PCIe?

Hi all thanks for thinking with me.
@Cool GTX pointing to the hybrid helped i found that allow wake up for tasks was on (updates and the sort) which had a default start time after midnight and guess when i mostly turn off my pc :D
So disabled this and also set al usb devices on disabled for wake up pc.
did not happen to half boot up this time. after 3 minutes to be certain did take off main power.
Hybrid boot i had previously after initial install already disabled as it is a pain in .....
 
@GGTV-Jon not certain if the killer ethernet allows wake up did not check this yet.
 
If it does happen again i will try without the 4 pin floppy plug to power the additional usb2 card.
Might be a cause. i dit notice my keyboard and mouse powered down now which was not the case previously before these settings so it might already be solved.
 

I have a similar problem. If I shut down win10 normally, then I have post code "C" for about 1-2 min.
It is noticeable that this is in connection with Corsair AXi 860W and Seasonic Prime Platinum 1300W.
 
I had a BeQuiet Straight Power 11 850W on a test basis and the problem did not occur.
 
I suspect the motherboard has a problem with certain power supplies