My laptop's CPU is an Intel P8400, rated for operation at 2.26GHz.
However, sometimes it starts running really slow: the computer becomes nigh unusable, and utilities like CPU-Z show clock speeds in the range of 192MHz to 533MHz.
After a while, it will recover. Sometimes it will recover spontaneously, but often I have to reboot it (usually more than once), or shut it down and come back later.
It doesn't seem to be overheating:
- SpeedFan and the BIOS both shows reasonable temperatures.
- The problem occurs most frequently when turning on or waking up the computer after it has been off for a while.
- Leaving the laptop running for a while to "warm up" sometimes fixes the problem (temporarily, of course).
- The fan does not spin up, and the air coming out of the computer is cool.
I have also eliminated software and drivers as possible causes:
- I updated the drivers under Windows 7.
- I updated the BIOS to the latest version (even though there was nothing relevant looking in the release notes).
- I also tried turning off Intel SpeedStep, but it didn't fix the problem, so I turned it back on.
- I gave up on Windows 7 and installed Ubuntu 11.10 instead.
- I eventually noticed that my BIOS setup reports the current clock speed, with a ridiculous readout like this:
- Current clock speed: 192MHz
- Minimum clock speed: 1.6GHz
- Maximum clock speed: 2.26GHz
None of these changes had any affect on the problem that I could detect.
I'm guessing that either the motherboard (likely) or the CPU (possible) has failed, but I was wondering if anyone here has ever seen symptoms like this. I've Googled around a bit, but all I'm finding is stuff related to overheating or overclocking.
What could be causing this behaviour? Is there any way I can fix it short of replacing the laptop?
My laptop's specifications:
- Dell Latitude E6400
- Intel Core 2 Duo P8400 (2.26GHz, dual core, 45nm, 3MB cache)
- Intel GM45 motherboard chipset
- 4GB of DDR2 800MHz RAM
- 9 cell extended battery (in good health according to the BIOS)
- About 4 years old (out of warranty)