Not heard of this before myself but I've been wrong before! If it were the other way round then you may suspect it was due to playing at a higher resolution, but that doesn't really explain this case.
In general, the fact that it reboots during games suggests a temperature/power issue.
HWMonitor from CPUID is a good utility for monitoring all of your hardware and will also show you the temperatures of most of your components:http://www.cpuid.com/hwmonitor.php
If you can post results at idle and at load (run prime95 or other stress-test utility) then that would help.