Hi all,

I was going through the book Linux Administration Handbook by evi nemeth, et al

in it is written that ideal operating temperature for computer equipment is (17c-20c) with about 45% humidity.

ambient temperature about 27C in the computer room imply about 49C inside machines. commercial grade chips have an operational range up to about 120F, at which point they stop working; beyond about 160F(71C) they break.



my questions are as follows:-

1) on what basis it is said that ambient temperature about 27C in the computer room imply about 49C inside machines.
is it based on any empirical formula ?

2) Can any one point out some good guidelines for cpu temperature settings / server room temperature settings ?

The melting point of silicon is around 150C.
The problem is, you can't measure the centre of transistor junctions. Sensors have mass and therefore take time to heat, etc.

The engineering approach is to treat the chain [Silicon --> Package --> Heatsink -->Ambient] as a series of 'resistances' specified in degrees C per watt. Read an IC manufacturer Application Note for details. A heatsink of 2.5 degrees C per watt dissipating 20 watts would be 50 degrees above ambient - get the idea?
http://www.ferrotec.com/technology/t.../thermalRef05/
http://www.thermshield.com/.../Basic...esentation.pdf
Then the commonsense approach superimposes itself. Allow 25-35 degrees per stage. CPU Critical is set at 105degrees, heatsink about 70 degrees C. These are absolute maxima. Lower is better, as it avoids thermal cycling (= aging) of components..