Even P3's had thermal protection, although it was less advanced than P4's throttling it still protected the chip. At a certain temp (I believe around 120 degrees, but not 100% sure) it simply puts the cpu into "sleep mode" crashing the computer, but protecting the CPU.
Pretty sure that all P4's include two later protection, firstly the throttling which can be partially ignored/adjusted based on bios settings, and secondly an emergency "halt" mode which like the P3's protection shuts down the CPU in the event the gracefull throttle didnt work.
Pretty sure that all P4's include two later protection, firstly the throttling which can be partially ignored/adjusted based on bios settings, and secondly an emergency "halt" mode which like the P3's protection shuts down the CPU in the event the gracefull throttle didnt work.