[SOLVED] Difference Between Clearing CMOS Through Battery Removal vs. Loading Optimized Defaults within the BIOS?

Iver Hicarte

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May 7, 2016
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Good day,

What is the difference between resetting the motherboard's BIOS through physical resetting through the removal of the CMOS battery vs. just loading the optimized defaults through the BIOS itself. Did some research and what most people say is that they're basically the same. But isn't removing the CMOS battery a "thorough "and a more "hard" reset than just loading the optimized defaults within the BIOS since we're physically removing something from the motherboard. I need to reset my motherboard, like I mean...a hard reset. I'm having issues and I want to thoroughly reset it. So is it worth the hassle through removing the CMOS battery, or will I achieve the same by just loading the optimized defaults through the BIOS itself?

Thanks.
 
Good day,

What is the difference between resetting the motherboard's BIOS through physical resetting through the removal of the CMOS battery vs. just loading the optimized defaults through the BIOS itself. Did some research and what most people say is that they're basically the same. But isn't removing the CMOS battery a "thorough "and a more "hard" reset than just loading the optimized defaults within the BIOS since we're physically removing something from the motherboard. I need to reset my motherboard, like I mean...a hard reset. I'm having issues and I want to thoroughly reset it. So is it worth the hassle through removing the CMOS battery, or will I achieve the same by just loading the optimized defaults through the BIOS itself?

Thanks.
They may just be the same thing...but they may not. It can most likely be different with different systems too.

CMOS is just a memory storage so you can think of it like a desk with pigeon holes for storing 'stuff' in. When BIOS needs to know which option to use for a particular setting it just pulls something from the pigeon hole that's supposed to relate to the setting and uses what it finds in it without asking if it's logical to the hardware installed or any other settings. When you change hardware or update a BIOS what used to be logical in the related pigeon hole may no longer be so you need to reset CMOS to force all settings to be logical with each other to allow it to at least start up in a BIOS screen whereupon you can do a 'load optimized defaults'.

The 'load optimized defaults' might go through and force settings into an 'optimized default' setting that's supposed to work with any configuration hardware. But it might be different from a reset as it may just reset a subset of only those settings that are exposed to a user in the BIOS screens. Resetting CMOS forces all of the CMOS 'pigeon holes' into an as-new state which has to be a default since it's the same state it would be in if it were just manufactured and never powered on before, with only the first BIOS upload having been performed. So I suggest to always do a CMOS reset after hardware change or BIOS update and then do a 'Load Optimized Defaults' too.

The strange thing to me is sometimes you also have to pull the battery to get CMOS to fully reset to a pristine, first power-on, configuration. Not sure why that is and it's seemed to only come about with the AM4 platform.
 
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Good day,

What is the difference between resetting the motherboard's BIOS through physical resetting through the removal of the CMOS battery vs. just loading the optimized defaults through the BIOS itself. Did some research and what most people say is that they're basically the same. But isn't removing the CMOS battery a "thorough "and a more "hard" reset than just loading the optimized defaults within the BIOS since we're physically removing something from the motherboard. I need to reset my motherboard, like I mean...a hard reset. I'm having issues and I want to thoroughly reset it. So is it worth the hassle through removing the CMOS battery, or will I achieve the same by just loading the optimized defaults through the BIOS itself?

Thanks.
Clearing CMOS by post or button copies BIOS to re-writable memory (that's what CPOS is) BIOS itself can only be changed by flashing other version. All your dealings are with CMOS, not BIOS directly. There you can make changes to settings without actually changing anything to BIOS itself.
Lading the optimized defaults is similar but with settings manufacturer deems to be necessary for proper operations. Depending on BIOS there may be several steps including some for performance. It may not be exact copy of BIOS.
Newer ones may not change date and time or even some hidden settings. That can be done only by taking CMOS battery out for some time (until all capacitors discharge), pressing Start button for few seconds speed that time up.
PS.
ALWAYS make sure that PSU is right OFF. either by PSU switch or unplugging from mains.
PS2.
Some BIOS may require both, first reset by posts or button and then remove battery.
 
Good day,

What is the difference between resetting the motherboard's BIOS through physical resetting through the removal of the CMOS battery vs. just loading the optimized defaults through the BIOS itself. Did some research and what most people say is that they're basically the same. But isn't removing the CMOS battery a "thorough "and a more "hard" reset than just loading the optimized defaults within the BIOS since we're physically removing something from the motherboard. I need to reset my motherboard, like I mean...a hard reset. I'm having issues and I want to thoroughly reset it. So is it worth the hassle through removing the CMOS battery, or will I achieve the same by just loading the optimized defaults through the BIOS itself?

Thanks.
They may just be the same thing...but they may not. It can most likely be different with different systems too.

CMOS is just a memory storage so you can think of it like a desk with pigeon holes for storing 'stuff' in. When BIOS needs to know which option to use for a particular setting it just pulls something from the pigeon hole that's supposed to relate to the setting and uses what it finds in it without asking if it's logical to the hardware installed or any other settings. When you change hardware or update a BIOS what used to be logical in the related pigeon hole may no longer be so you need to reset CMOS to force all settings to be logical with each other to allow it to at least start up in a BIOS screen whereupon you can do a 'load optimized defaults'.

The 'load optimized defaults' might go through and force settings into an 'optimized default' setting that's supposed to work with any configuration hardware. But it might be different from a reset as it may just reset a subset of only those settings that are exposed to a user in the BIOS screens. Resetting CMOS forces all of the CMOS 'pigeon holes' into an as-new state which has to be a default since it's the same state it would be in if it were just manufactured and never powered on before, with only the first BIOS upload having been performed. So I suggest to always do a CMOS reset after hardware change or BIOS update and then do a 'Load Optimized Defaults' too.

The strange thing to me is sometimes you also have to pull the battery to get CMOS to fully reset to a pristine, first power-on, configuration. Not sure why that is and it's seemed to only come about with the AM4 platform.
 
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