Bitcoin is using +90% CPU power using Ubuntu 12.04? I am using Ubuntu 12.04 and Bitcoin client v0.8.6.0-g03a7d67-beta and Qt version 4.8.1 as the GUI.

My CPU is heating up and is automaticly shutting down after 30 minutes and sometimes after many hours. This is occurring  both while synchronising with the block-chain or while reindexing the blocks on disk.

After the CPU overheating my laptop (Dell Inspiron R15) switches off and has corrupted my sync. Other users have mentioned to start by typing in terminal bitcoin-qt -reindex. At the the end of the index around week17 my CPU overheats again.

Reading around I found topics about switching off the "generate bitcoin" option inside the bitcoin.conf file but on my Ubuntu (including hidden files) I can not find that file.

Any tips or help on this overheating issue?  I have also posted this on AskUbuntu

Thanks in advance.
Using bitcoin-qt you can go into Helps->Debug Window->Console and then type 

setgenerate false


By default it should already be false so my guess is that you have a fast internet connection and that your computer receive a lot of blocks in a short time. Your computer then needs to check all the ECDSA signatures for the transaction and this can consume a lot of CPU.

I had an overheating issue like that when I was mining litecoins with my laptop. I installed the cpufreq package to decrease my cpu frequency about 30% and everything was fine then.

If you have a dual-core processor you should type something like this in your terminal.

sudo cpufreq-set -c 0 -u "1.8GHz"
sudo cpufreq-set -c 1 -u "1.8GHz"