Usually, BIOS settings in most laptops are set so that fans run only when the temperature is quite high. This is usually done so that battery life can be extended — fans having physically moving parts require significant amount of power to run. It is well known that high temperatures will reduce the life of electronic parts by putting them under temperature induced stress. Therefore, using the fans in the manner configured by default will result in lower life expectancy and sudden catastrophic failure in devices such as the mother board, CPU, Hard disk drive, graphic accelerator card etc. Therefore, I would recommend that temperature be maintained as low as possible even at the cost of continuously running fans. That would mean access to A/C power source and possible failure of fan. But a simple cost-benefit analysis will show that the cost of the fan is far lower than the cost of the other devices and the possible data loss in the event of a failure.