In-game and Rivatuner Statistics FPS Lock/Cap Comparison

This time I&trying to compare In-game FPS lock with third party program called Riva Tuner Statistics Server (RTSS) in order to see which software performed better, specifically about Frame Time. What you&expecting to see is when i capped FPS on 30 frame/second, a frame will only stay for 33.3 ms before proceed to show you the next frame. While Riva Tuner can hold perfectly 33-34ms (As in graph that&hard to see), the In-game fps cap have a rate of 25-55ms, which means a frame appear longer than other frame or maybe stay shorter than other frame. thus make the game feels jittery and stuttering. Specs: - Ryzen R5 1400 3.2GHz Up To @3.4GHz - Galax EXOC GTX 1060 6GB - 8GB RAM DDR4 2133MHz - 1TB HDD 7200RPM - AsRock A320M HDV R4.0 - Antec NeoECO 550W, 80+ Bronze PSU Thanks For Watching!