LCDs images delayed compared to CRTs ? Yes ! (page 4: 3 cases and conclusion)

Back to option 1 : the easy way

We will have the best reaction time with the Vsync option OFF as the card progressively sends the calculated information to the monitor. There is however one little delay (less than one image) for the display due to calculation times.

Vsync OFF is the optimum solution. The problem is that it introduces ruptures in images. Aesthetically, it is less nice. Very often mostly with LCD, we activated the synchronisation of the card with the monitor. The monitor displays images only when they are fully calculated. It is nicer, but the framerate is reduced (we are restricted by the monitor refreshing rate, or 60 fps for 60 Hz like most of the monitors) and the delay increases. This time it is 2 whole images (on average).

The last solution is that some use Triple Buffering to smooth the framerate. This solution, which is less and less used, increases the delay to 3 images (on average)!

Lastly, there is the monitor. We voluntarily neglect the processor calculation time to simplify the analysis.

Conclusion of the delay chain, three possibilities

In the end, if the optimum solution is chosen, we will have one Razer Copperhead mouse, one graphic card with V Sync OFF and one CRT. The delay will be 1ms + 0.5 images (with a frequency at 100 Hz, it will be 1/100/2= 5ms) + 0 = 6 ms. Less than one image of delay, which shouldn´t be perceptible.

Standard solution: a good USB 1 mouse (all Microsoft´s, most of Logitech´s, the cheap razer) + V Sync ON + average LCD, type Dell 2407WFP monitor. The delay is now 8 ms + 2 images (LCD = 60 Hz, or 33 ms) + 24 ms = 65 ms. Almost 4 images late!

Unrecommended solution: slow mouse + Triple Buffering + slow monitor (Acer AL2032W). 16 ms + 3 images (3 x 16.7 = 50 ms) + 44 ms (the longest delay measured with the Acer monitor) = 110 ms, or 6.5 images late!!!

Where does this delay come from? It’s hard to tell for now and we will have to investigate a little more. Nevertheless this new test sends us back to our previous article: Panels a la carte: Mura, components, dead pixels.... Almost certainly, the quality of electronic components must play on the monitor reaction time. And as we said before, these electronic components have a direct influence on the quality of monitors. It has an influence on the longevity of components, color quality in time, rate of dead pixels, and Mura effects. We will have to add to the list the problem of reactivity measured on most monitors. Anyway, we have found here a new test to add to our procedure…

Thanks to Marc and Damien for their help … and patience.