When i do gaming for over an hour under Windows 8 not the CPU, but the GPU becomes too hot.
Yesterday i've reached 122 C° playing at simraceway, that is definitely too hot, but i also know that GPU-Z can be wrong, at that temperature the Mac would shut down itself
i have to say that in all other situations, temperatures go pretty well, with CPU around 36 degrees and GPU around 53-55 when idle. when in heavy use but not gaming, temps never go over 80 degrees