First, notice here that there is definitely a change from our FRAPS based reported frame rates and our capture-based frame rates. The blue line on the Observed FPS graph has several places where it dips lower than the FRAPS FPS graph; an indicator that we are seeing some runt or dropped frames (check the final 10 seconds or so). Even though the average frame rate is drastically improved at over 110 FPS, the frame times graph shows some strange jumps DOWN to nearly 0 ms frame times. Further investigation was needed.
Well, it appears that NVIDIA’s GeForce GTX 760M, running in tandem with the Intel Core i7-4702MQ processor is exhibiting some frame issues. As a quick reminder, using a technology called Optimus, NVIDIA attempts to seamless transition between the integrated and discrete graphics options on-board. For this to work, the frame buffer from the NVIDIA GTX 760M must be transferred to the main memory of the system which is where the frame buffer for the IGP is. This allows the images rendered by the GTX 760M to “pass through” the integrated processor graphics and connect to the same output / display. That is a simplification of the process of course, but it gets at what I think is the problem here.
Let’s see another example though with DiRT 3.