XC-603 power issue

adladladl

We have an Acer Aspire XC-603 desktop (Pentium J2900 2.1GHz).

It was powered off over night and the next day, power on would start to boot, then it would power off again. Sometimes it would boot into Windows then power off again.

I put in a new power supply, but that had no effect.

After several power-on attempts, I can sometimes get into the BIOS (version P21-B1C1). If I get into Advanced Settings and PC Health Status, all the voltages are wildly fluctuating. For example, +5V goes from 2.9V to N/A to 6.9V... jumps all over. The other 3 voltages are behaving similarly. +12V goes to 3V then to N/A then to 16V, etc. 

When I check the power at the power connection (from the power supply), they are all what they should be and stable. After about 2 hours of doing this yesterday, the voltages finally stabilized in the BIOS display, and I was able to boot. The system stayed up all day (and I took a backup of the C: drive). I powered down overnight, and today it's back to the power fluctuations and won't stay up (if I can even get it to start to boot). I've done a reset (removed the CMOS battery, pressed power on, wait, etc.) with no effect.

I used to see similar behavior in older PCs with bad capacitors on the mother board. But in those cases, it was easy to physically see the bad caps (bulging, leaking, etc.) but I don't see anything like that on this MB. At this point, my only thought is a bad mother board, but I wanted to check with the Acer community to see if anyone has seen this before and if there was any other solution. I've reseated memory, checked all the cables and connections, but nothing seems to be an obvious fix. I haven't tried reseating the CPU, but I can. Final resort might be to order a replacement mother board.

 I really don't want to replace this with a new system since it belongs to a business and there are a lot of applications that would need to be reinstalled, reconfigured, etc. 

Any other suggestions ?

billsey

Do you have peripherals plugged in that might be causing excess draw? Fluctuating power usually means the PSU is flaky, but you've already addressed that. That means it has to be related to the draw and that's either the MB (maybe with an almost short) or something else plugged into the system. Running with nothing plugged in except the monitor, keyboard and mouse might help decide which it is.

adladladl

All that's connected is the HDD and a DVD (other than KB and Mouse). If I unplug either (or both) HDD and DVD, it won't even power up to BIOS. The CPU fan starts spinning, but it never tries to boot. I'm going to try a different HDD, but like I said, the +5, +12, etc. at the power connector from the PSU to the MB are all what they should be and clean.

adladladl

Strange symptoms:

1) With either the HDD or DVD disconnected from power (or both disconnected), it won't even power up to BIOS even though all the power from the PSU to the MB measure as expected. I did replace the HDD with a different one and it exhibited the same power issues. But I've never seen a system that won't boot to BIOS if the HDD or DVD aren't connected to power.

2) When I do get to BIOS, the power as shown from the PC Health Status display are wildly fluctuating

3) If I do get it to boot to Windows and I run HWMonitor, the power looks right (see attached screen pic) 

4) If I do get it to boot to Windows, it seems to stay up. But as soon as I try to reboot, it starts the "power-down" stuff again. It takes multiple tries to get it to really boot.

adladladl

Well -- it's getting worse... now it won't POST at all... guess a new MB is needed.