TR Forums

After 5 years it was bound to happen, I've experienced my first non-obvious hardware failure.

I have very little experience with diagnosing these so any help would be greatly appreciated.

During use my computer immediately turned off and would not start. Upon pressing either power or the memOK button on my ASUS P8P67 PRO motherboard, the CPU LED and BOOT DEVICE LED would both light for a moment, and the CPU and GPU fans would just begin to spin, before immediately stopping after about half a second. Further attempts to power on yield no response until power is cut and then restored. As long as power is on the motherboard power LED will stay on green, regardless of what happens.

I have tried clearing CMOS, reseating all connections, testing one RAM stick at a time, removing both sound card and graphics card, and removing all but the two motherboard power connectors, with no change in result.

I have visually inspected everything and can see no broken components and cannot smell any electrical smoke.

I'm hoping it's the power supply, which would be the easiest component to replace, I'm wondering what other TR forumites might think the problem is. It seems to me that it's either the CPU (somehow so messed up it is interfering with post before it even really begins), the motherboard (not finishing a post attempt due to being broken), or the power supply (broken in a manner which prevents it delivering any significant amount of power).

I'll be testing with a difference power supply tomorrow morning, any help would be greatly appreciated, thank you for your time.

Did you plug or unplug a USB device at the moment of failure? If so, shine a flashlight into the ports and make sure a pin didn't break or bend.

Beyond that, it really does smell like a power supply problem, although to be sure, strip the system down to just the mainboard, CPU, one stick of RAM, keyboard, and video (if onboard video available, use that and pull the GPU as well). All other power cables, data cables, peripheral cards, and USB devices need to be disconnected from the power supply and/or motherboard. If it boots normally, there's probably a short somewhere else in the system. If still same behavior, probably means PSU, with the motherboard being next.

Also check around the motherboard for any capacitors that have obviously failed, after five years an ordinary EOL failure is entirely possible. These would usually give general instability warnings a long time before enforcing an outright lockdown, but it's still something to check.

I've had some more tests done and its the motherboard. I still don't know why its messed up but its the only component that won't function when swapped to a test bench(got a bit of help from a computer store). Power supply chugs along fine when put in another system.

Oh well, off to the ASUS RMA department.

EDIT: got an advanced RMA set up, should be up and running in a day or two, thanks for the help.

For future reference, you may want to get your hands on a speaker. When you have problems, your motherboard will beep it out for you. Then you just have to look up the post codes.

It did have a connected speaker actually, but the motherboard was shorting in some way which didn't even allow the motherboard to attempt post, let alone fail to post, so the speaker never gave a signal.