So, I have had lag whilst playing games under windows (CoD , AoC , L4D) and changed my video card drivers to nvidia's. This helped a bit, but not enough. I read somewhere that the problem is likely due to heat problems, to install smcFanControl and then restart. I did exactly that and it works fine, but the only problem is I am not sure how safe it is. For games like Age of Conan, (with reasonably high graphics) it will need high fan speeds, I have it set to near the maximum on all 3 options (ODD - 4k , HDD 4k , CPU 2.4k) Is this safe or should I spend a while finding the best fan speed before lagging? The noise doesn't bother me so don't include that in your reasoning. Edit: I am using a 24" iMac 3.06ghz, with 4gb RAM , 500gb 5400 rpm HDD and nvidia 8800 GS 512mb card.