PC no longer boots without CMOS clear

Toastylee123

Toastylee123

Toastylee123

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Joined
19 Nov 2020
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31
Hi,

PC has been running fine with no issues for a few years now (spec below) with only change being the addition of M.2 boot drive over a year ago but no issues since, but suddenly last week it stopped powering on at all (no fans turn or anything) when the button is pressed.

Power is getting to the pc, and the idle led's on the gpu flicker when pressing the power button so it does appear it's "trying" to boot, but otherwise nothing at all happens. If i clear cmos, it then boots without any problems at all.

So far i've tried replacing the battery, and updating bios to no effect. Worth noting is that it will reboot fine so long as the power supply doesnt lose power from the wall, which happens every night as it's turned off at the wall.

My next port of call would be to replace the motherboard as the problem appears to be bios/cmos related, but i'd rather seek a second opinion before having to pay out for that.

R7 3800X
MSI B450 Tomahawk MAX
16GB (2x8) 3600Mhz Corsair LPX
Asus 1080TI Strix OC
Corsair RM Series RM 850 '80+ Gold' 850W Power Supply
WD Black 1TB SN750 M.2
WD 4TB Red Pro 7200rpm
 
You should not be turning off at the wall and sounds like the Caps in the PSU are draining overnight so empty when you do so.

My 1st thought was the battery but you said you swapped it, it could be the Mobo but try a spare PSU 1st.
 
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Thanks for the reply, wasn't aware of any issue with a pc being turned off at the wall (to be clear, it's shut down properly before power is cut), but isn't really an option to leave it plugged in overnight.

Sadly I don't have a spare power supply with which to test so failing any other diagnostic steps i'm missing, might just had to get a new board and hope for the best
 
A modern PC is not really off (Win 10) when you power it down (by default) and you think its using much power or going to burn the house down?
 
Lol nah, the reason it gets turned off is because it's in my room, and the breaker in the plug makes a slight electrical buzz while on. It's barely audible but is enough to stop me from sleeping.
 
Well to power it down without changing settings you need to Hold SHIFT and then click Shutdown in menu, right now you are basically unplugging it while it is in a Hybrid Sleep mode which may be the issue.
 
Try a different bios version as I had a similar issue on V39 where after updating it would try power on and the fans would start but then completely stop again. I had to take the battery out for 10 mins as even shorting the jumper didn't seem to work but I updated to the later beta one and it seemed to work fine after that.
 
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Looks like i spoke too soon, over a week of no problems, and the exact same problem has now started to occur on the new motherboard, so might be looking at a psu now, though given it responds to a cmos clear, i have strong doubts about the psu being at fault
 
It's uncommon but you CMOS battery could be goosed, you should be able to get a replacement to test nice and cheap.

BAH, didn't read the whole thread, just seen your last post and then accidentally quoted myself instead of editing, time to sleep :D
 
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