Originally Posted by frito
wondras video card port delay is normal your card is pretty fast at only 4 ms but some have shown as much as 16 ms delay in clone mode, in the main post i cover this in the testing instructions.
Yeah, it's definitely not unusual. The fact that it only occurred with mixed VGA/DVI interfaces was the surprise.
in regards to SMTT your reading it incorrectly
how it works and why its so accurate vs other timers is that every single timer is in sync within the program (they show the same reading at the same time) but V-Sync is disabled and actual frame rates are very high so as your display refreshes from top to bottom the timers continue to advance. the result is timers will increase as you go from the top of the screen to the bottom of the screen and you can always see where the oldest number and newest numbers meet is where oldest updated number and newest updated numbers are all the ones before the latest number are meaningless
It's not that I'm reading it incorrectly, it's that I'm looking for something different.
Since a given pixel on a 60Hz display is drawn every 17ms, the timer value should increase by that amount between frames. When you look at just one monitor in any SMTT picture, if a row has a ghost image from the previous frame, the time difference is always 17ms.
What I'm saying is that if the two monitor outputs are exactly
synchronized, i.e., each pixel is created at exactly the same time for both screens, the number being displayed on a specific row
will be the same for both outputs. The delayed values will be a multiple of 17 behind, just as for the previous frame on the single screen. If the difference is not a multiple of 17, then the outputs are not being created in sync, so you know you have a delay between ports. In my case the differences were about 20, indicating a 3-4ms delay.
This is different from measuring the actual input lag, where as you say, you look for the highest number on each screen, regardless of which row it's on.
Since they are usually on different rows, the difference won't be a multiple of 17.