Question Why does new CMOS battery drain so fast ?

xxdms2k11xx

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Oct 23, 2013
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I tried to replace the new CMOS battery as it always drains & resets bios settings.

Sometimes my pc won't turn on, only the motherboard light or you have to wait 30 mins to turn on.


Does my PSU or motherboard have a defect?

Here are my specs:

CPU: AMD Ryzen 7 5800x (NEW)
MOBO: Asus ROG Strix B550-F (Wi-Fi) II (Version 2803) (NEW)
GPU: GTX 1060 6gb (3 Years old)
Elgato 4k60 PRO MK.2 (NEW)
RAM: Corsair vegeance rgb rt 4x8 DDR4 3200 (32gb) (NEW)
AIO: Deepcool Gammaxx L360 A-RGB (NEW)
M.2: Samsung 970 Evo Plus 1tb NVMe (NEW)
HDD: 4 TB Western Digital (Green) and 1TB Western Digital (NEW)
PSU: Seasonic focus + 750 watts (Gold) (3 Years old)
 

Colif

Win 11 Master
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Jun 12, 2015
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I don't think the PSU can do it as it would need to go through MB circuitry.

Its more likely its the motherboard

 
Rapid draining of CMOS battery can be caused by improper earthing (grounding) of the computer. Get an electrician to check if this is the problem.
I'm curious how improper earthing of the computer could cause the CMOS battery to discharge. The ground or earth wire to the computer should NEVER carry any currents as it's a safety feature intended to completely trip the branch circuit off line if it should. If it's completely missing, or poorly connected, it would simply not carry any currents...not even the current from the battery to discharge it.

Still...it's always good practice to make sure the system is properly grounded for safety.

The battery is internally connected (on the motherboard) to the CMOS NVRAM chip and RTC circuits through a current limiting resistor and steering diode (or something similar). There's plenty of opportunity for failure in any of those devices to run the battery down fast.
 

Phillip Corcoran

Titan
Moderator
I'm curious how improper earthing of the computer could cause the CMOS battery to discharge. The ground or earth wire to the computer should NEVER carry any currents as it's a safety feature intended to completely trip the branch circuit off line if it should. If it's completely missing, or poorly connected, it would simply not carry any currents...not even the current from the battery to discharge it.

Still...it's always good practice to make sure the system is properly grounded for safety.

The battery is internally connected (on the motherboard) to the CMOS NVRAM chip and RTC circuits through a current limiting resistor and steering diode (or something similar). There's plenty of opportunity for failure in any of those devices to run the battery down fast.
I read that could cause the problem on two other forums so thought it worth mentioning that's all. Not based on my own theory or experience.
If it's bunkum, I defer to your greater knowledge without question.
 
I tried to replace the new CMOS battery as it always drains & resets bios settings.

Sometimes my pc won't turn on, only the motherboard light or you have to wait 30 mins to turn on.
....
Do you get a defect notification? That would be some trouble-shooting LED's which might be the motherboard light you're seeing. Check your manual to see what that light means.

And yeah, just putting it on an ESD mat won't ground it. You need a ground wire attached directly to the PSU/case...that wire is furnished in the three-wire power cord that attaches with a three-prong plug to the wall outlet. The ground at the wall outlet should be reliable and that's why you need an electrician to check it out like @Phillip Corcoran suggests.

An alternative as a test is to run a wire from a copper water pipe to the case of your computer. This is temporary, just a test, to see if it helps any or if at all. This won't work if your house has plastic/PEX water pipes which is most likely only in newer construction
 
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