I think your having a bad temp like rgd1101 said,you can use Speedfan
http://www.almico.com/speedfan.php to check the temp of the cpu,don't know if this support the gpu temp so if it doesn't you can use gpu-z http://www.techpowerup.com/gpuz/
Run your games then alt+tab then check your temps,tell us what the result is!