What makes Games Crossfire enabled ?

[Buckster]

for instance

FSX only uses one GPU (I have a 3870x2) - therefore performance is a bit limited

rename FSX to FEAR.exe and it then uses both GPUs, but performance is halved !

but run Lock-on (no renaming) and it uses both GPUs and I get almost free FSAA - so can run 8xAA, 16xAF, etc etc

now surely Lock-on - old as it was doesn't have the architecture to uses dual GPUs - so how does it do it ?

but FSX can't ?

confused

 

[Monkeynut]

ATI have to put the specific crossfire optimizations into their drivers for each game. So work without the proper profile, but most don't. It's ATI who do the crossfiring, not the game.

 

[Buckster]

mm - thanks Monkeynut

so why optimize a 3 yr old game like Lockon (not that I'm complaining)

and not something like FSX ??

 

[Marky]

Because it's a classic and many people still play it I suppose Not sure why they haven't done FSX yet =\

 

[chaparral]

From what i have read on here...FSX is meant to be very CPU limited....

 

[Monkeynut]

That would make sense, with all those pathways for the planes it has to calculate.

 

[Buckster]

FSX may be CPU limited at lower resolutions

but at 1900x1200 with FSAA it sure strains the GPU !!

 

[Renegade87]

FSX is heavily CPU limited espically the higher the setting, all the GPu has to do is basicallly skin the world. The CPU actually use a lot more thana noermal game. If you have a lot of AI on in FSX you will get a massive CPU hit.

It came down to the fact that with the limited time the MS Aces team had to devleop the game and service pack they felt that enabling sli and crossfire consume more time than gives in profornace.

Anyway the biggest factor for FSX gpu wise is the amount of VRAM avalible especially with the high complex meshes and the larger screen resolution.

 

[Rroff]

Basically older games will typically work with multi GPU rendering techniques without any extra tweaking from the game or drivers mostly because they use fairly non-complex rendering which works very well with SLI/Crossfire - whereas newer games use more complex techniques (buffer object manipulation, post processing, etc.) that aren't straight compatible with plain old multi-GPU rendering and need specific support in the drivers or programmed with multi-GPU in mind.