You'd experiencing thermal throttling when you reach unsafe operating temperatures...these would appear as artifacts.
So, building up on The Paladin's answer, are experiencing these?
Tj. Max...the junction temp should be your real reference in this case. Download Core Temp and it will show you the junction temp...if I remember correctly it is around 100 - 105 degrees for ivy bridge cpus. in which case you are quiet far from it and okay.
For Sandy - Ivy cpus...most Intel experts would suggest 72 - 74 Celcius as nice & within the operating range temps.
let us now what turns up. Bottom line is that your cpu would rather shut itself down then burn and the failsafe would protect is almost certainly.
enjoy your games
Regards
Satyam