Erratic system clock on T42

[RolfThinkPad]

I have a strange symptom on a T42.

In the BIOS the system clock does not count the seconds evenly: every four or five seconds there is a pause for about a second. Then it "catches up" with the counter going quicker. Hard to explain, but something like a dance; normal-normal-normal-slow-slow-quick-normal...

Importantly though, it keeps perfect time (I monitored it with my quartz watch over periods of a minute).

I have also noticed that the Windows "select harware profile" option that comes up at boot, the 30 second countdown timer is vey slow - significantly more than real seconds.

Also in Windows XP, the second hand and counter on the Windows Date and Time clock does the same as the BIOS clock.

I have never seen this before. Any suggestions?

[Johan]

Although I haven't seen what you describe, I would assume that it could be caused by an almost flat (= near-dead!) BIOS battery... unless your CPU runs 100 % with no overhead for the RTC (real-time clock)?

If you wish, try replace the BIOS battery - see System service parts - ThinkPad T40, T40p, T41, T41p, T42, T42p for part numbers (cheap on eBay).

The T42 Hardware Maintenance Manual will show you how to do. Also, see the instructional videos at Hardware removal and installation - ThinkPad T40/p, T41/p, T42/p, T43/p.

Johan

[RolfThinkPad]

Hi,

Thanks.

I was beginning to think the CMOS battery was involved. (A Seiko watch for example will warn of a fading battery by the second hand jumping in 2-second steps, although Seiko document this and it is deliberate. This led me to think about battery issues.)

In a way I will be glad if it is the battery, as it is far less serious than other issues.

Thanks also for the hardware info; I have the relevant manuals and have dissected a T40 in the past, so I know what's involved.

As for the T42 performance, it performs well and there are no errors/warnings in the system event log.

I'll update this post when there is a conclusion.