Mystery CMOS

By hector ·
On a new G965 motherboard the following:
The CMOS losses its settings if the power is unplugged from the power supply. The CMOS battery delivers 3.2v and have been replaced. Power measured between CMOS battery & Bios chip is 3.2v. Any suggestions, Gigabyte support have never seen something similar.

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Failing CMOS

by mjd420nova In reply to Mystery CMOS

I have seen this before. There is a small capacitor connected paralell to the battery and it may be loading or shorting the battery. In normal situations the capacitor will hold a residual charge long enough to remove and replace a weak battery without losing the BIOS settings. If this capacitor has failed then the CMOS will default as soon as the power is removed from the circuit.

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Missing Capacitor

by hector In reply to Failing CMOS

Please excuse my ignorance when it comes to this subject.
There is a small cap where you said, but please explain why the CMOS losses it's settings when you disconnect the power from the PSU, although the CMOS battery supplies voltage to the bios chip. I noted on some other Gigabyte boards that the cap in question haven't even been mounted, only marked. Thanks for your intelligent reply, beats the one I got from Gigabyte support by far.

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Another thing to check

by IC-IT In reply to Mystery CMOS

Is that sometimes the board will come with the CMOS reset Jumper in the clear position.

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Reset Jumper

by hector In reply to Another thing to check


All Gigabytes boards nowadays comes without any jumper close to the pins, I assume the situation refered to in your reply must have been causing some problems.

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Hmmm Thats Funny

by IC-IT In reply to Reset Jumper

I just looked at a 965G-ds3 and they have a clear CMOS jumper right next to the battery.

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The jumper mystery

by hector In reply to Hmmm Thats Funny

Give or take a year, it's been probably 2 years since the last time I saw a CMOS reset jumper on a Gigabyte motherboard, whether it is a localized thing for South Africa I won't know. On avarage I handle 15-20 Gigabyte boards a month and in the beginning I thought it funny. The manuals also refer to Gigabyte not even supplying the jumper "to avoid improper use of this header".

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Checksum issues

by herbert.jeremy In reply to Mystery CMOS

Also having issues,this one has me beat. PC runs fine during week days, boots ok. When the unit is shutdown for the weekend, Monday morning it comes up with a checksum issue.

First thing i did was replace the cmos battery, this stopped the issue for a couple of weeks then it reappeared.

Next was to return the MB for a replacement (this was going to take 4 weeks from gigabyte so ended up just buying a new motherboard). 2 weeks again and the problem has returned.

Have done memory tests and all is ok, Visually checked capacitors, motherboard, looked for shorts on the casing but cant see any problems. Seems to me that over the weekend its draining power from the cmos, during the week its ok because its being used every day. When the checksum issue happens, a simple restart fixes it... but why is this happening??? any ideas?

BTW this is the 3rd gigabyte system i have seen this happen on (the other 2 were fixed with a replacement MB). Hence we are not building systems with gigabyte components anymore.

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Re: Checksum issues

by herbert.jeremy In reply to Checksum issues

FYI. No solution was provided by gigabyte, replaced MB with different model, problem fixed. So possibly a bad batch of MB from gigabyte... who knows

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