It’s been more than two decades ago ( in 1980 to be exact ) since Seagate produced the first 5.25″ harddrive. Fan and heatsinks for CPU have existed quite a long time ago.
A few years back, graphic cards began shipping with their own heatsinks. You have fans for CPU casing too nowadays. No need to mention the power supply. Of course it must have it’s fan.
But only just recently did we see a cooler for harddrives!
Overheated harddrives means problems. Normally your harddrive’s temperature should be around 45°C degrees and below. If you wish to measure your harddrive’s temperature, try downloading hdd thermometer v1.3 here
If you have more than one harddrive, never place them one on top of the other. Give it some space!
For Seagate harddrives, this is what Seagate says “All Maxtor ATA, SATA, and SCSI drives can operate with or without a fan, providing the hard disk temperature does not exceed 131°F (55°C) as measured from the top cover of the drive. Reliability will be compromised when the drive is exposed to temperatures above 55°C or 131°F. When in doubt of your system’s ventilation capabilities, or ambient environment of your hard disk, add an extra cooling fan to the drive bay or system case to force air across the drive.“