Here are some notes that I had floating around. Generally, but not always, the Product Specification Sheet for the product will list the operating temperature range for the product in question.

* Processor Spec on AMD 4850e: http://products.amd.com/en-us/Deskto...il.aspx?id=426
Operating Temperature: < 78 deg C

* Intel on Chassis Temperature: http://www.intel.com/support/process.../CS-001553.htm
Keep fan inlet temperature < 38 deg C
Recommended to keep chassis temperature below 40 deg C

* Specification of Western Digital RE2: http://www.wdc.com/en/library/sata/2879-701176.pdf
Operating Temperature 5 deg C to 55 deg C


* Specification of Crucial SSD: http://www.crucial.com/support/ssd/ssd_25_specs.aspx
Operating Temperature 0 deg C to 70 deg C

A large number of people seem to aim for whatever the current temperature is minus a couple more degrees.

[edit: line spacing]