Bad Caps? NetVista 6841

[JustMe]

I have a problem with one of our PC's that just started this morning.
The computer continually re-boots if sitting "idle". If I can log into Windows before it re-boots and start something processor intensive, the machine will run for hours without (apparent) error. If I close the application the re-boots resume.
The re-boots also occur from a DOS prompt after booting from a floppy (if the system is idle) so I guess I can rule out the OS and drivers. If I run any system diagnostics on the MB or RAM from the DOS boot the system stays alive and the tests run without error.

Bad Caps?
It seems strange the system stays up under heavy load and only starts acting up when idle. Temp is not a factor as the problem occurs when the system is hot or cold.

IBM NetVista 6841
1Ghz PIII
512MB
Windows 2000 Pro

[Topcat]

Sounds like a classic case. I've personally seen a LOT of Netvista's with the plague. I'd pop the side off the case and have a looksee at the caps.

[JustMe]

I checked the MB and most of the caps near the CPU have swelling on the tops, one appears to have leaked a bit (brown spot on the top). I will have to take a better look in the AM when I can find my cheaters (eyes aren't what they used to be) and see if I can get the values off of them.

[Topcat]

That being the case, there's no doubt as to the problem. Needs to be recapped...

[MD Willington]

I just recapped mine a while back...

The three smaller ones near the chipset.

Runs like a champ now...

MD

[JustMe]

The three caps near the chipset look OK, they are only 470uF.

Most of the 13 near the CPU are swelling with a couple leakers, these are 1200uF & 1500uF caps.

Is it advisable to replace the 470uF's also?

This machine went downhill pretty fast, will not even boot today.

I have two more of these systems on the network, guess I better open those up and have a peek at the boards.

Would adding a case fan to these systems keep the caps going a little longer? IBM designed these with only a CPU fan and the PSU fan to cool the system.

[MD Willington]

Your board may have a slightly different layout than mine, my board has a cpu fan header and a system fan header.

MD

[JustMe]

The board has headers for both the CPU & system fans. IBM did not utilize a system fan in the 6841.
I have a few 80mm Vantec Stealths in the drawer, I think I will install one in the others systems when I check the MB for bad caps, couldn't hurt!

[Topcat]

The three caps near the chipset look OK, they are only 470uF.

Most of the 13 near the CPU are swelling with a couple leakers, these are 1200uF & 1500uF caps.

Is it advisable to replace the 470uF's also?

This machine went downhill pretty fast, will not even boot today.

I would recommend replacing all 1000uF caps and up. 470uF caps are not prone to failure like the higher values are, but it has happened on rare occasions. The lower value caps seem to be made from a different electrolyte, as I've seen the same brand 1000uF caps fail, while the 470uF caps will live forever... I wouldn't worry too much about them, unless they're showing the physical signs, such as leaking or domed tops.

[JustMe]

I replaced the 1200uF & 1500uF caps and the board has been working great for over a week.

Thanks Chris!