PDA

View Full Version : Strange slowdown with 6800GT in Doom3


Wavern
08-11-04, 07:38 PM
I'm locked at 60fps most of the time at 1280x1024 no AA. I did stumble across a few areas where the fps drops suddenly.. and I'm curious as to why. It seems that it knocks the fps down exactly in half.. a bug?

Here are screenshots of a problem area:
http://wavern.com/v-web/gallery/albums/album01/shot00007.png
http://wavern.com/v-web/gallery/albums/album01/shot00008.png
(nearly a meg each so just the links)

All I did to recreate this is to strafe to the side by a foot. Any ideas on why?

Golden Sample
08-11-04, 07:42 PM
Hi

It`s because VSync is on ;)

IF you can`t reach the full 60`s for a second, for example 56 fps instead of 60, it`s cut in half. Don`t ask my why, it has something to do with not beeing able to use tripple buffering in OpenGL like ATI can.

Turn of VSync, and try it!

Sven :nanahump:

Wavern
08-11-04, 07:54 PM
Yup, same spot gives 56-57fps instead of 60.. which is strange as well but acceptable.. unfortunately the tearing of no vsync is not good! =vP

Fx-Rat
08-11-04, 08:44 PM
Yea I have the same problem and when you say slow down you mean even though the frams drop to 40 or 50 I slow down walking to a really slow pace its like when I go buy steem comming buy out of the pipes or comming threw doors whitch is quite often. other than that it runs really smooth after I put the command line com_fixedtic 1 in console.

svemirac
08-12-04, 01:36 AM
To avoid this problem, you'll have to enable "tripple buffering" in your video drivers. With vsync on and default(double) buffer, if you cant reach 60fps, your fps slash in half even though you just lost 1 fps60/2=30, 30/2=15 etc.... With tripple buffer, if you u lose for instance 2 (or any amount) fps, it'll render (58) the actual amount of fps on the screen.

saturnotaku
08-12-04, 07:37 AM
To avoid this problem, you'll have to enable "tripple buffering" in your video drivers. With vsync on and default(double) buffer, if you cant reach 60fps, your fps slash in half even though you just lost 1 fps60/2=30, 30/2=15 etc.... With tripple buffer, if you u lose for instance 2 (or any amount) fps, it'll render (58) the actual amount of fps on the screen.

But there is no way to do this in NVIDIA's drivers or through a program like RivaTuner. So far this seems the top of people's complaints about the 6800. In ATI's drivers you can force triple buffering in OpenGL (but not in D3D).

gsgrunt
08-12-04, 07:51 AM
I dealt with this issue a bit differently.
My monitor can do 1280x1024@100 Hertz. By using RivaTuner to force the max refresh rate when playing games, if the FPS drops below the 60 FPS cap instead of getting a drop all the way down to ~30FPS (60/2) I get ~50 FPS (100/2)

habicht
08-12-04, 11:34 AM
@svemirac

pls can you tell me (us) how to enable "tripple buffering" ...

thanks a lot!