I want to troubleshoot an Asus ROG Strix Z270I mini ITX mainboard that won't power on. It could've been water damaged but there is no obvious corrosion or burnt components. The orange standby LED (SB_PWR) is on but shorting the power button pins does nothing - the board doesn't even turn on the PSU, so the diagnostic LEDs won't help because they're all off without main power. This is what I checked so far:
In case it's relevant, the other components are an Intel 6700K with a water block, 2x16GB DDR4 RAM (don't remember the model) and some Samsung SSD. If the mainboard can't be saved, I'd also have to change the CPU turning it into an expensive upgrade...
- The PSU is good and turns on when manually bridging the pwr_on pin to ground in the 24-pin ATX plug.
- The power button header on the mainboard has 3.3V on one pin (ground on the other), so at least some of the standby circuit must be working.
- Forcing the PSU on manually (see first point) while it's plugged into the board doesn't start the boot sequence (no diagnostic LEDs turn on).
- The BIOS battery was flat (2.4V) - I replaced it but it didn't change anything (nor should it). That also means the BIOS settings were reset without making a difference.
- I removed everything from the board and tried to get it to turn on completely barebone (no CPU, no RAM, no drives) - only with the 24-pin and 8-pin power plugs connected, but same result. The board should at least turn on the PSU and get stuck at some boot error (CPU/RAM or so) with no components installed, right?
In case it's relevant, the other components are an Intel 6700K with a water block, 2x16GB DDR4 RAM (don't remember the model) and some Samsung SSD. If the mainboard can't be saved, I'd also have to change the CPU turning it into an expensive upgrade...