Typically - "stock" fans are the bare minimum for what the card needs in order to perform properly. What brand of 4670 card is it?
Few issues which could cause this:
- Fan RPM [speed] not correct [too slow or not speeding up when the GPU gets hot] - you should be able to use a program to monitor the speed
- Fan not mounted correctly to the GPU - visual inspection - remove the video card and verify the fan is not loose.
- Thermal Grease between the fan and GPU incorrectly applied at the factory - Excessively thick applications of thermal grease will do more harm than good by interfering in the heat conduction between the cooler and CPU. The thermal grease layer should be thin and cover the whole surface you will only need about half of the amount in the tube included.
