Cause analysis of black screen failure caused by CMOS battery failure

Symptom: The unit of a compatible machine, using a motley motherboard, chipset for the INTEL810,CPU Celeron 733MHz, not often used. Recently I have to reload the system, after a few days, suddenly appear unable to boot the phenomenon: Press the Chassis power button, the optical drive, hard drive indicator light, optical drive can not be out of the warehouse, the hard disk does not appear to read the sound of the disk, the monitor black screen, and can not power button to turn off, you must unplug the

Troubleshooting: According to the author's previous experience, the causes of this black screen phenomenon generally have three kinds: chassis power failure, motherboard failure, CPU problems. So the author first measured the output voltage of the power supply, ±5v and ±12v are normal, will it be power shortage? Removing the power from the other computer will not solve the problem.

I do not have the appropriate motherboard and CPU can be used to replace. So after power off again, power supply fan, CPU fan whistling, looking at the display without movement, I think the point of failure is where? After a few minutes, the screen suddenly lit up, the machine began self-test, the result is incorrect: CMOS Checksum error (CMOS checksum errors). Into the CMOS settings, found that the original changes to the set has become the default value, the author reset, self-test normal through, smooth access to the operating system, it seems that the CPU should have no problem. Through the system can be shut down normally, power off and then boot, still appear above phenomenon. It seems that the problem must be on the motherboard. CMOS settings cannot be saved, then the CMOS battery may have failed. Remove the battery a measure of its voltage, only 0.9V, far below the nominal value of 3V.

The author has also seen the failure of the CMOS battery failure, generally only appear "CMOS Checksum error Report", set lost, but will not lead to a black screen phenomenon ah. Let's change the battery first. After changing the new battery, the author reset CMOs, repeated test, the fault is completely ruled out! It seems that the CMOS battery failure will also cause black screen, I hope the author this troubleshooting experience can give you encounter the phenomenon of black screen friends bring some experience.

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