One of our notebooks (IBM ThinkPad T42 from pre-Lenovo days) - running Windows - has started intermittently losing power. No STOP message. Nothing in the Event Log. Just blacks-out and reboots.

I suspect overheating CPU since it only seems to black-out when on AC power. On battery the Power Management switches the CPU to slow-speed and so far I haven't experienced a black-out like this. The battery condition is good and it will run several hours on battery alone.

I've checked the fan unit. The fan is spinning at what appears to be full-speed and quietly. I've removed the fan module, checked the thermal paste between it and the CPU surface, and remounted it firmly.

I've set the CPU to slow speed in the BIOS but this appears to be overridden by the IBM Power Scheme Settings after bootup. The control panel wont accept anything but "Maximum" for the CPU speed in the AC mode.

This notebook recently had a problem with it's internal Intel PRO/Wireless LAN adapter. Which was solved by upgrading drivers. That problem caused intermittent crashes with BSOD. Is it possible the Wireless card is physically damaged and with the new drivers is causing black-out-power-off instead of BSOD?

migrated from serverfault.com Aug 19 '09 at 13:51

This question came from our site for system and network administrators.

  • 1
    Shouldn't this rather be on superuser? – Joey Jul 18 '09 at 13:35

It happened to my T60p, exactly what you said, but it was a RAM module in my case. It would work fine on battery, but would suddenly black out on AC. I eventually replaced the faulty module, but as a quick fix, I uninstalled the Power Manager.

Also, try just disabling the adapter and see if that solves the issue. If it does, then you got your root cause. hth.


  • It was exactly this problem. A faulty RAM module. I was able to boot from a USB thumb drive I formatted as bootable (the CDROM on this notebook was also broken). And I was able to run memtest outside of protected mode and confirm exactly which of the 2 SODIMMs was at fault. The problem has now stopped. – rwired Jul 25 '09 at 10:48

I would try booting it with a Linux live CD like Knoppix or Ubuntu 8.04, 8.10 or 9.04.

Leave it on AC power.

From the terminal you can do: (Ctrl+C to stop it)

cat /dev/urandom > /dev/null

This will bring CPU usage up to 100%.

If it doesn't freeze it's a software related problem in Windows, otherwise it's a hardware issue. Ubuntu also offers memtest. You can pick it at boot time from the grub menu: it's a good test for RAM in case you suspect a faulty module.

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