Z170 Extreme 4 only starts after pulling power

Murdock9 wrote: Hello all I've got a bit of a problem here: I build a new system a few months ago including a Core i7 6700k, Kingston HyperX DDR2666 RAM and a "different brand" Z170 Board. The old motherboards Bios was a disaster so I decided to return it and buy an ASrock board. The board of choice is the Z170 Extreme 4 now, nothing else in the system changed. Everything seemed to work fine at first but as it turned out unfortunately the PC does not boot anymore after I shut the system down in Windows. The lights and fans come on, but nothing happens. I have to pull the power plug for about 10 seconds before it starts working again. This happens every single time, so it's nothing random, the debug LED then shows "00" (Make sure CPU is installed and reset CMOS). Interestingly enough, rebooting from within Windows works fine, the problem only occurs when I shut it down. Resetting the CMOS did not help, the Bios is updated to the latest version. Seeing as my system did not have any stability related issues with my other components before, I assume this is caused by the new motherboard.  Any ideas would be much appreciated.

Are you using the same Windows installation you used with the other Z170 board? What version of Windows?

Three things you wrote catch my attention, to paraphrase:

Starting the PC from a cold start/shutdown gives you a 00 POST code, consistently.

Removing the power plug and trying again results in a successful start of the PC, consistently.

Restarting/rebooting the PC works fine, the problem happens only after a shutdown.

The 00 POST code means a non-functioning or missing CPU. We will also see a 00 POST code if the 12V ATX 4/8 pin CPU power cable is not connected to the board. I'm not saying you don't have this cable connected to the board, you obviously do. I just want to make the point, no power to the CPU results in a 00 POST code.

Removing AC power from the PSU via its AC power cable temporarily fixes your problem. Does the power switch on the PSU being set to Off also fix the problem, or only removing the AC power cable?

When a PC is shutdown, the PSU is still providing some power to the board, via the +5V standby power source in the PSU. So the PSU in not completely shut off in this situation, a small amount of AC power is being used by that part of the PSU. Removing the AC power cord of course completely shuts off the PSU, but also resets it or has it starting up "fresh".

A restart or reboot does not interrupt the PSU's usual operation in any way, it never stops providing power on all three voltage rails. A shutdown does interrupt the PSU's normal operation, the main voltage rails are shut off, and the +5V standby power source is being used. So there is a big difference between a shutdown and a restart to the PSU, they are completely different.

The point of all of this is to make you wonder about the PSU. The board itself could also have some kind of problem, but I would not dismiss the idea of trying another PSU with that PC. If a different PSU changes nothing, then we know it's not the PSU. If you don't try another PSU at some point, it remains a question.

Hello all


I've got a bit of a problem here: I build a new system a few months ago including a Core i7 6700k, Kingston HyperX DDR2666 RAM and a "different brand" Z170 Board.
The old motherboards Bios was a disaster so I decided to return it and buy an ASrock board.


The board of choice is the Z170 Extreme 4 now, nothing else in the system changed. Everything seemed to work fine at first but as it turned out unfortunately the PC does not boot anymore after I shut the system down in Windows. The lights and fans come on, but nothing happens. I have to pull the power plug for about 10 seconds before it starts working again. This happens every single time, so it's nothing random, the debug LED then shows "00" (Make sure CPU is installed and reset CMOS). Interestingly enough, rebooting from within Windows works fine, the problem only occurs when I shut it down. Resetting the CMOS did not help, the Bios is updated to the latest version.

Seeing as my system did not have any stability related issues with my other components before, I assume this is caused by the new motherboard. 


Any ideas would be much appreciated.

Edited by Murdock9 - 16 Aug 2016 at 5:54pm