Vsynch was screwing me.

[Hurin]

Howdy All,

I don't consider myself a noob. But this will probably come off as a noob question.

I usually have vysnch disabled in all the games I play. Yet a lot of people are saying to enable it for Doom 3 (presumably because it is already capped at 60fps in the engine).

Well, I turned it on. . . and then couldn't figure out why --while playing at 1600x1200-- I'd be cruising along at 60fps. . . and then drop to 43fps. . . almost always one or the other.

So I turned the resolution down to 1280x1024. . . and noticed that things stayed at 60fps quite a bit more often. . . and when they did plummet, they nearly always stayed at 50fps.

Then it hit me:

At 1600x1200, my refresh rate is 85. And half of 85 is 42.5 rounded up to 43.

At 1280x1024, my refresh rate is 100. And half of 100 is 50.

So, when things slow down, Doom 3 appears to vynch things down to half your refresh rate. Is that correct?

Anyways, I turned off Vsynch, and now @ 1600x1200 I rarely see anything below 50fps. And I see very little tearing. I really have to be looking for it.

So, does vsynch really work that way? I had no idea it would essentially go either 60 or half your refresh rate (and then lower if need be). . . leaving all that juicy performance in between totally moot.

Thanks,

H

 

[BobbyD]

Yep that's how it works. Same thing got me. It will lock your fps to your refresh rate if you can draw that many frames, but if you can't then it will lock it at a divisor of your refresh rate.

I never used Vsync in any other game, but this game had some awful tearing so I used Vsync. I noticed that my fps would always be either 60 or 30, although it rarely dropped below 50 without Vsync. I made some posts on some other forum and someone else answered this for me. I thought something was bugged at first. The default refresh rate is 60Hz unless you have it overridden in your drivers. I guess the combination of 60Hz and 60fps was causing the tearing, because I just upped my refresh rate to 85Hz and now I don't notice any tearing without Vsync.