Any part that is operated above its maximum temperature rating over a prolonged period of time will see its MTBF drastically lowered. All parts that make up a modern PC have such a maximum temperature rating, most of which are around 50…65 degrees Celsius, or 122…149 degrees Fahrenheit. An average CPU dissipates about 50-watts of heat inside a PC case and is one of the major contributors to a rise in system temperature which could easily be as high as 45 C/ 113 F. If the case temperature is already that high, some of the parts of the PC could already be operating at or above their maximum temperature rating.

Especially 7200-rpm harddisks are suspect as they are known to get substantially hotter than their 5400-rpm counterparts. Naturally 7200-rpm and multiple platters all contribute to more heat being produced, as the spinning platters get hot due to the friction with the surrounding air and the heat dissipated by the spindle motor, the more platters and the higher the rpm, the more heat. Unfortunately we can’t simply say that 7200-rpm harddisks get hotter than 5400-rpm harddisks by default as our measurements will clearly show, but we’ll get to that in the next few pages.



Fig 2. The interior of a typical 80GB 7200-rpm harddisk, in this case a Maxtor D740X. This harddisk features two platters with 40GB/platter density and a total of four read/write heads.

What is important to consider though is the question whether the harddisk doesn’t get too hot when mounted inside the PC. Most modern harddisks have a maximum operating temperature ranging from 55 to 65 C or 131 to 149 F, and if operated above that temperature you’re really putting yourself at risk of losing valuable data or a harddisk malfunction. If the system temperature is already at 45 C/ 113 F the harddisk could very well be operating over it’s maximum temperature, which will cut into the disk’s MTBF and reliability significantly.