There is something wrong with your system. My
E6400 is loaded (2.8, Nvidia), and I never even near 80C. While running at max load with an overclocked gpu, I am still under that. My GPU can be at 95 and my CPU at 75 and no throttling at all.
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Dell Latitude E6400: Intel Core 2 Extreme X9100 3.06GHz, Nvidia Quadro 160M, 4GB DDR2, 160GB @ 7200RPM, WXGA+ LED, Backlit KB, 9Cell
Dell Inspiron 5150: Intel Pentium 4 Mobile HT 3.2GHz, Nvidia Geforce FX Go 5200, 1GB DDR, 60GB @ 7200RPM, SXGA+ CCFL
Latitude E6400 Cooling+Performance Guide