Dead PSU vs MB?

[schwatschko]

A friend has been having a problem recently:

Computer wouldn't start up, waited a few months and tried it again and it worked. Same problem occurred last night, reset CMOS and computer booted up again.

Is the power supply failing as it gets older? MB can't be dead as it boots up here and there, right?

Going to try a new PSU I've got today. It's a Dell XPS 9100.

Thanks for any suggestions!

Max

 

[rolli59]

Resetting CMOS is for the board not the PSU so possibly the board.

 

[Ubrales]

Check by using a different, known good PSU, and you can be certain.

 

[ubercake]

May need to replace the CMOS battery on the MB. Tried that yet?

 

[schwatschko]

Resetting CMOS is for the board not the PSU so possibly the board.

May need to replace the CMOS battery on the MB. Tried that yet?

Where would I buy a CMOS battery and are there different types? How do I know which to buy? Also, if it did die, would it ever cause the PC to not boot properly?

Thanks for the help!!

 

[schwatschko]

Check by using a different, known good PSU, and you can be certain.

I'll give it a shot tonight!

 

[rolli59]

Resetting CMOS is for the board not the PSU so possibly the board.

May need to replace the CMOS battery on the MB. Tried that yet?

Where would I buy a CMOS battery and are there different types? How do I know which to buy? Also, if it did die, would it ever cause the PC to not boot properly?

Thanks for the help!!

Here http://www.computerhope.com/issues/ch000239.htm

 

[arcitech1]

Your CMOS battery has a code number stamped on it like CR2032 (or similar), drug store, wally world, radioshack, hardware stores, they all carry this style of battery (sometimes called button or watch batteries because they were most common in wrist watches before the age of personal computers and they look like a large button).

 

[InvalidError]

Where would I buy a CMOS battery and are there different types? How do I know which to buy? Also, if it did die, would it ever cause the PC to not boot properly?

99% of motherboards use a CR2032 cell for RTC/CMOS battery and you can usually find those in drugstores or just about any place that sells watch batteries.

But a PC should still boot with a dead CMOS battery or no battery at all. All it will do is cause your PC to boot with default settings, displaying a CMOS checksum error and a dead battery warning. Press F1 or whatever key the BIOS asks to resume and that should be the end of it.

For random boot failures (or successes), my first suspect would be the PSU. Yes, PSUs do tend to fail over time. In my personal experience, they are the first thing that fails about 80% of the time.

 

[schwatschko]

Where would I buy a CMOS battery and are there different types? How do I know which to buy? Also, if it did die, would it ever cause the PC to not boot properly?

99% of motherboards use a CR2032 cell for RTC/CMOS battery and you can usually find those in drugstores or just about any place that sells watch batteries.

But a PC should still boot with a dead CMOS battery or no battery at all. All it will do is cause your PC to boot with default settings, displaying a CMOS checksum error and a dead battery warning. Press F1 or whatever key the BIOS asks to resume and that should be the end of it.

But why would resetting the CMOS let the PC boot in this case? In any case, I'll try the PSU and CMOS tonight and post what happens!

 

[InvalidError]

But why would resetting the CMOS let the PC boot in this case? In any case, I'll try the PSU and CMOS tonight and post what happens!

It could simply be coincidence.

Or it could be that the PSU is so far gone that the PC is unable to boot when settings get restored from CMOS almost as soon as the computer comes out of reset state and clearing the CMOS delays normal operating parameter restoration (by probing the hardware instead of reading from CMOS) just long enough to pass that point.

 

[rolli59]

Un-selected best answer above since not selected by OP and there is no solution to the problem yet!

 

[schwatschko]

After throwing a new PSU in for the friend, it's running perfectly again! I guess it just died over time, and throwing a new 700w in was the fix. Thanks for all the help and suggestions all!