The PAE in 64-bit systems is for PCs with more than 16 EB of RAM, which is almost 17 million terabytes. Now, although you can consume more than that amount, you won't be able to have execution threads that consume more than 16 EB, which is, without a doubt, a limitation to keep in mind.

Si no hay buen contacto entre el disipador y el procesador si que hay riesgo, porque no estaría disipando bien el calor y el procesador alcanzaría temperaturas muy altas, lo cual le restaría vida útil o podría quemarlo directamente. Saludos