I have been quite frustrated with my Toshiba M700 for the last couple of months. It never seemed to run as well as it should with the CPU maxing out at 100%, the battery going very quickly and the casing getting hot.

I had deliberately bought the M700 as a desktop replacement but I was at the point where I was just about to but a desktop anyway because I thought it was beyond the M700 to run two external monitors. I even thought about a Mac Book Pro until I saw the price.

I noticed that while the CPU was maxed out the Windows 7 Resource monitor was showing that the CPU frequency was only around 40% of the maximum attainable. I downloaded coretemp which showed that one of the cores was running at 103 C and I noticed that there was a correlation between the temperature and the CPU frequency – the system was throttling the frequency at these extreme temperatures.

Image:Fixing an Overheating Toshiba M700

Being worried that it was a problem with Windows 7 I booted it to Linux from a USB drive. This was inconclusive so then I restored an old XP backup, Initially I thought that I had solved the problem but the machine was still running at 103 C although the throttling didn’t seem so bad ( it is harder to measure in XP ). I still felt something was wrong.

Anyhow, being an Engineer I felt that there was something not quite right so I decided to take it apart, as you do. I found some good instructions here which helped, particularly with the keyboard connection.

Everything around the heat sync looked pretty clean and I almost gave up but when I blasted it with compressed air for good measure quite a lot of debris flew out. I rebuilt the machine – try and remember where the long bolts came from ! – and now it is running very very happily on windows 7 at 55 C and it feels like a powerful machine again.

If you are having similar problems It might be worth shooting some air into the fan vent. There is a hatch to give access but the access is not really that good.

Strangely I have just tried to re-create the problem by blocking the vent and cant get it to be bad enough to get past 90 C. It just shows how a small amount of dirt can clog the heat exchanger very effectively.