--- wtz ---

Be careful when reading datasheets The 70C temp rating is external environmental temperature (say the case temp of your system) and is for when operating the devices at worst case conditions (highest power consumption in this case... no pun intended). The 1W power rating is for that same worst case condition of 70C.

All of it put together (power & temp) is based on keeping the junction temperature of the actual semiconductor device below a certain temperature (usually 125C for ICs). So, if your case is 40C instead of 70C, the parts can handle more than 1W. If your cooling is better than a bare chip in no air flow, it can handle more than 1W. Hence the use of fans on the chips when we OC and well ventilated cases

You also need to be careful on power calcs... all the current isn't dynamic current (based on frequency)...

Regarding the testing side of things... accelerated burn-in when properly done can be accomplished in 24 hours to get past the 90% point of the infant mortality stage. 160 hour burn-in is the point under less stressful conditions. BTW... here's a link that will start to explain infant mortality and burn-in processes to greatly reduce them in products. Notice the failure % without burn-in btw... Figure 4 of the link.

Peace