ATI vsync bug with ArmA?

[[frl]myke 14]

Hi all,

i have a strange bug in ArmA with my Radeon HD4870 Graphic Card. I guess the problem lies at the Card and not at ArmA particulary.

But before i start let me check if i understood the general function of vsync correctly.

So, theoretically a GPU runs as fast as it can, giving a max of FPS depending on its performance. So if the GPU can handle it, 300FPS is also possible as 25FPS. Always depending on the game engine and the GPU performance.

Now a Screen has a fixed Framerate, somewhat around 60hz and 75hz (might give others but it is not that important for now).

If now the GPU runs at 80FPS (which is equal to 80hz) and the screen runs at 60hz, it happens that the screen does mix to following frames into one, making the frame look teared. So vsync should make sure, the GPU delivers a frame when the screen is ready to show a new frame (can't explain it better but you get the point).

This also means that the FPS is limited to the screens framerate (also not the correct word, i know) or to a double or triple of it.

With vsync deactivated, there shouldn't be such a limit and the GPU renders as fast as she can but with the risk of teared frames.

So far so good.

The following issue happens on a Sapphire Radeon HD4870 with 512MB VRam. Driver is most actual Catalyst 9.4 but the issue was also with previous drivers.

I've checked it several times, the setting "wait for vertical refresh" is set to "Always off".

Now to not risk that it is just the GPU not going further i've set all settings to very low and viewdistance slider to full left on 500m. Also i've stared in the sky so there were no objects to draw except the sky itself.

The FPS does not go over 75FPS as 75hz is the vertical refresh rate of the screen. I've asked some clanmates as they have 8800GTX Cards and they say at least on the map it goes up to 300FPS.

So it seems as this is an issue between ATI cards and ArmA. Is there someone who can confirm this issue or even has a fix for this? Or am i looking at a complete wrong spot?

And as second thing (which i guess this problem is related with the above and will probably be fixed if the above is), whenever i turn myself ingame about 180 degrees, i get framedrops from ~50FPS down to less than 15FPS for about 1-2 seconds before they go up to 50FPS again. Does anyone else have/had this behaviour?

Oh and for completeness: ArmA is patched to 1.14. Beta 1.15 isn't an option since i play MP on our Clanserver which runs Linux and as you know there isn't a 1.15 server for Linux out yet.

[SWAT_BigBear 0]

The FPS does not go over 75FPS as 75hz is the vertical refresh rate of the screen. I've asked some clanmates as they have 8800GTX Cards and they say at least on the map it goes up to 300FPS.

With ArmA, 75 is excellent.

Who says they get 300?

I only have to turn VSYNC off if I have SLI enabled. I've never seen above 75 even though my monitor is just 60hz.

[[frl]myke 14]

SWAT_BigBear,

thanks for your post but this doesn't help me. It's not that i want to have 75+FPS, i would raise viewdistance if i had that. Overall performance is good and i wont complain about.

But as i wrote i have the issue when turning myself ingame about 180 degrees, FPS drops below 15FPS for 1-2 seconds. And my guess is that those 2 issues are related to eachother (no prove, just a hope).

So by hunting this "vsync-limit-bug" down i hope also this framedrop issue might be resolved. I know it doesn't sound pretty logic but let me have my hopes.

So please, i'm asking here for help, not opinions.

:EDITH:

And when hitting "M" ingame and you look at the map, 300FPS is pretty normal with a decent PC.

[SWAT_BigBear 0]

So please, i'm asking here for help, not opinions.

:EDITH:

And when hitting "M" ingame and you look at the map, 300FPS is pretty normal with a decent PC.

I wasn't giving you my opinion, I'm giving you another "8800gtx" users in game view.

My fps drops during turning also, not as severe but there are several factors that can change the fps in ArmA dramatically, such as time of day, weather conditions, looking from bright sun and turning to a vehicle, trees ect.

You said you get 75fps looking at the map, mine drops to about 40, even if I had 70 before looking at the map.

Are you measuring fps in SP/map editor, or while playing on a server?

Edited April 13, 2009 by SWAT_BigBear

[[frl]myke 14]

Sorry BigBear, got you wrong.

I try to describe the framedrop as detailed as possible. First of all, SP/MP/Editor doesn't matter, happens everywhere. The effect is everywhere clearly visible, no matter where i am on the map (Sahrani). Happens in Paraiso also as in the open or in woods.

So i'm standing there, looking straight north, FPS are around 45. Then i turn myself and look straight south. The FPS drops below 15 for about 1-2 seconds. Then it goes back to around 45.

Then when i turn again to the north, the same drops occurs. I do not move otherwise, i just turn on place.

Ok, the first time i turn around, the engine has to reload objects and textures for the objects that were behind me and therefor not visible, fair enough.

But it isn't limited to the first turnaround, it happens all the time.

Somehow i think it is related with the limiting to the vsync issue. Can't explain why and i might be horribly wrong.

But fact is, if vsync is disabled in the driver, ArmA shouldn't limit the FPS to screens vertical sync. So this is a bug anyway (but i still guess it lies in the driver) and i would like to know if there's a fix or workaround which eliminates it.

So there are 2 bugs i'm hunting:

- FPS drop when turning around

- FPS limit even with vsync disabled

Thanks again BigBear and sorry again, wasn't my intention to offend you.

[kklownboy 43]

Sorry BigBear, got you wrong.

I try to describe the framedrop as detailed as possible. First of all, SP/MP/Editor doesn't matter, happens everywhere. The effect is everywhere clearly visible, no matter where i am on the map (Sahrani). Happens in Paraiso also as in the open or in woods.

So i'm standing there, looking straight north, FPS are around 45. Then i turn myself and look straight south. The FPS drops below 15 for about 1-2 seconds. Then it goes back to around 45.

Then when i turn again to the north, the same drops occurs. I do not move otherwise, i just turn on place.

Ok, the first time i turn around, the engine has to reload objects and textures for the objects that were behind me and therefor not visible, fair enough.

But it isn't limited to the first turnaround, it happens all the time.

Somehow i think it is related with the limiting to the vsync issue. Can't explain why and i might be horribly wrong.

But fact is, if vsync is disabled in the driver, ArmA shouldn't limit the FPS to screens vertical sync. So this is a bug anyway (but i still guess it lies in the driver) and i would like to know if there's a fix or workaround which eliminates it.

So there are 2 bugs i'm hunting:

- FPS drop when turning around

- FPS limit even with vsync disabled

Thanks again BigBear and sorry again, wasn't my intention to offend you.

Drops are not a bug, its just that ARMA is more than your system. North Island(united sarani) and in some citys its just that way, no matter the setup.A bigger cpu it will be a much small drop, 3.8ghz and up is good.

On Vista sp1 playing ARMA with a ATI card (only tested/play with 4870s) you can not disable Vsync. Since the 8.12 drivers i think?

Actually your card will run better with some settings on high, the right combination is better than low. The big United Sarani Island can be problematic do to the amount of stuff it has, it takes a big CPU to get fluid with VD in the 3500 and up; gtx 285s or CF/SLi rigs to pull over 1600/1200 Res,with high settings ( AA for sure). Drops and slow downs happen, Its ARMA.

[SWAT_BigBear 0]

Thanks again BigBear and sorry again, wasn't my intention to offend you.

No offense was taken what so ever.

I was really questioning the "300fps" you were told someone gets, even if it is just looking at the map.

It's like kklownboy says, ArmA will push your pc to it's limits during certain scenarios, especially coop with lots of AI's on the move.

[[frl]myke 14]

It's like kklownboy says, ArmA will push your pc to it's limits during certain scenarios, especially coop with lots of AI's on the move.

Roger that. I know that pretty well. :D

And the 300FPS was just an example, not meant as "i also want 300FPS when looking the map". I would be happy if it just go above 75FPS.

It is more "why does it limit at 75FPS even when it should go higher". I just think this bug also take some performance and if it is resolved, i'll get better overall performance.

I just want to make sure there is no performance issue on my PC, thats all. I'm not hunting for as much FPS i can get as long it runs smooth. I'm just affraid atm it doesn't run as smooth as it could with the hardware i have.

[kklownboy 43]

Roger that. I know that pretty well. :D

...I would be happy if it just go above 75FPS.

It is more "why does it limit at 75FPS even when it should go higher"...

Its a Vista ATI driver issue and ARMA, You can not turn Vsync off. Since the 8.11s i think. Atleast it doesnt tear... and 300fps would have tears.

[desertjedi 3]

I looked up at a big white cloud and zoomed and I got 286 fps. That's with a GTX 260 with everything on Very High except Terrain Detail and AA (both high). So 300 fps would definitely be possible with a better video card.

If you're banging up against your refresh rate in frames then vsync must not be off regardless of what you're doing. I was told that the same problem exists in Arma for Nvidia (plus some other older games) and that the only solution was to use nHancer - and it worked.

The bad thing about vsync is when it supposedly halfs your frame rate if your frames drop below your refresh rate. Don't know much about that as I never have vsync on.