Review of the Dell 2407WFP-HC (page 3: Input lag in games)

2407WFP-HC : Input lag in games

If you didn’t already know, almost all LCD monitors have a small delay in display. To measure this, we photograph a chronometer which is precise to 1/1000th of a second displayed in clone mode on our reference CRT and the LCD we are testing. We take 12 consecutive differences, eliminating the two extremes and then find the average delay. The most reactive model measured up until now is the 22 inch Iiyama ProLite E2201W, which had no delay on our 12 measurements. Normally, we find a delay between 10 and 30 ms on most screens.

For this test, we deactivate graphic card / screen synchronization to capture a more precise delay instead a value that is rounded to the nearest image. For this reason, the resulting measurements are not dependent upon the fps value. An LCD functions at 60 Hz (even those that claim 75 Hz) and so a delay of 17 ms equals an average delay of a single image. In the same way, 33 ms equals 2 images. This may not seem like much, however, to an on-line gamer it could make a world of difference and, for example, an adversary with an LCD or CRT will see his character two images before him. This can be compounded by the fact that the mouse can add another 1 to 8 ms (except very poor ones), and the graphic card adds a half image delay (at best and actually this can be 5 to 50 ms). More specifically in our research we found that this can result in a total delay of 110 ms or 6.5 images. In this case, it is indeed noticeable and even bothersome for some gamers. For more details on this subject, see our article on LCDs images delayed compared to CRTs ? Yes ! .

This test applied to the Dell 2407WFP-HC and its rivals resulted in the following graphs :

PVA 6 ms : Dell 2407WFP-HC

TN 3 ms : Iiyama Prolite B2403WS

PVA 6 ms : Samsung SyncMaster 245T

MVA 8 ms : ViewSonic VX2435wm
The input lag measured on these large monitors isn’t that noteworthy. As we will see in on the next page, reactivity is satisfactory and all (at least the more recent versions) have a delay of between 2 to 4 images. Unfortunately, these results are rather stable.