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May 30th, 2025 02:20
PC won't turn on after 3 weeks unplugged, Optiplex 790 SFF
i had to leave home from early May and just got back home this week. tried to turn on the PC but didn't respond. i thought the CMOS battery finally gave up, so i replace it with the new one but still didn't respond. not even a single LED lights up. this is what i alr try:
1. replacing cmos battery
2. unplug and plug all the connectors
3. reseatting the memory
4. using BIST (built in self test) the PSU
when all cable connected, i tried BIST button but the light indicator didn't turn on. so i think the PSU is the problem, not the CMOS battery. i unplug all the cable that connect to the motherboard and do the test again, the light turn on and PSU fan is spinning, so the PSU isn't the problem.
i connect the 24pin from PSU to motherboard, do the test again, the indicator didn't give any response. can i assume that the motherboard is the problem?
anne_droid
3 Apprentice
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655 Posts
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May 30th, 2025 08:33
Hi
Most likely is the Main Board as you surmise.
Just as a precaution, disconnect all storage devices, peripherals keyboard, mouse etc etc, even any front panel connections and try again.
So the only connection is from the PSU. Power on for a few seconds and note the result.
Then if there is a response, add in the CPU fan, rinse and repeat for each and every device.
honeybadgrr
1 Rookie
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2 Posts
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May 30th, 2025 14:12
@anne_droid i tried connect all the cable inside and outside, only 24pin connector unplugged. and yes the PSU is working fine. so mainboard right?
i ask to the forum just to make sure before buying the replacement