Won't Boot

no1yak wrote: I have a Z97 Extreme 6 MB. On switch on it continually stops and restarts. I've tried it without memory, GPU and a new PSU and finally with a different CPU. The CPU fan runs and so do my two front case fans but the rear fan doesn't on switch on. Tried removing the cmos battery, no difference. So the thing just switches on and off. Can't even get to bios. Everything was working fine until I powered down. Anyone have any ideas on what I can try next. Thanks in advance.     Pete.

Did you clear the UEFI/BIOS with the jumper or CLR CMOS button on the board's IO panel? The button is the easiest way, just turn off the PSU, unplug it from AC power, let it sit for a minute, then press and hold the button for several seconds. That will reset the BIOS settings to their defaults, and you will need to reset any settings you use... if it starts and gets that far.

You said the PC starts and stops/restarts, which happens quickly I imagine, but did you check the Dr Debug display on the board for POST codes? It's located just below the blue heat sink for the chipset, at the lower right side of the board.

Do you get anything at all on your monitor?

If the rear fan that does not start is connected to the mother board, that is not a good sign about the board, which may have gone bad.

If you use a wired network connection, do you see the small LEDs next to the network input jacks light up when a cable is connected? That is, with the PC shutdown, but the PSU on?

You can try disconnecting power to all your drives, and disconnecting all devices on USB ports. With no keyboard or mouse connected, POST will fail and a code will be displayed, but if it got that far, that indicates a problem with one of those devices.

Removing/disconnecting components until you just have the CPU and memory in the board, will eliminate those parts as the cause of your problem. That includes the network cable, or wireless adapter.

The board will not start without memory, it cannot work without it. If you have some other memory you can use, remove your current memory and try just one DIMM in the A2 slot. Also clear the BIOS before starting the PC after changing the memory.

Electronic components can fail without any warning, and a mother board has hundreds of them. Their failure can be completely random and seemingly not related to any specific action, like powering down the PC.