The Asus Z97-A can occasionally display a CPU status light that remains illuminated even after it fails to post.
The Asus Z97-A can occasionally display a CPU status light that remains illuminated even after it fails to post.
The system runs a Z97-A motherboard with an i5 4690K processor, paired with a GTX 970 graphics card, an XFX TS 750W power supply, and two 8GB DDR3 sticks from Kingston HyperX Fury. My computer is around seven years old and has generally functioned well thanks to regular maintenance. The most recent issue has me confused.
About four months back, I experienced several random crashes, often accompanied by a message indicating the PC shut down due to the power supply unit. After cleaning the PSU, no further crashes occurred for four months.
Around two months ago, I began using a surge protector. There were some failed attempts to post, but I didn’t worry much since the issue resolved itself. A month prior, my PC stopped posting multiple times. Eventually, connecting the CLRTC jumpers helped, though the problem continued intermittently, often fixing itself about 70% of the time.
Then, after four weeks of stable operation, my PC suddenly restarted randomly—no logs or messages, suggesting it wasn’t a power surge.
Yesterday morning, the real issues began to appear:
- It would turn on with the CPU red light illuminated (no post) about 49% of the time.
- It would shut down after two seconds in 10% of cases.
- It would fail to turn on at all 35% of the time.
- Posting occurred 5% of the time.
- The system would cycle on and off 1% of the time.
No clear pattern or cause was evident.
I’ve tried reassembling, minimal booting, updating BIOS, disabling fast boot, cleaning contacts and dust, cleaning the PSU, and even stopped using the surge protector with old CMOS batteries. I’m still looking for other possible solutions.
Check the Reliability History/Monitor and Event Viewer for error codes or warnings before the issue occurred. These tools show patterns over time that might point to a problem with the power supply unit. Use the guides provided to explore entries further if needed.
The event viewer/reliability history doesn't show much useful information. It just lists some crashes I mentioned earlier. Recently, I managed to boot my PC a few times without issues, though the no-boot problem remains. I don’t want to keep restarting the PC 20 times just to get it working.
If past problems with PSUs exist, I’d want to replace the unit right away. Although the issue appears occasional, getting a new one would be a worthwhile investment that could be used in any future build if a reliable model is bought. Do you have access to a PSU you could test before buying? A friend or another PC?
That is a valid observation, and I think I'm going to do it as soon as I figure out the finances.
However, the PSU problems were only present when it was gunked up with dust, which I cleaned. Also, my boot is the only problematic part. When I actually do manage to post, the pc stays on and stable the whole day. I'd expect that a bad psu would be less stable.