2nd graphics card improves performance without SLI or Crossfire bridge....

[BeCubed]

As the title above describes I've run into this little anomaly and I'm trying to figure out why it even works in the slightest bit.

I found out the "hard way" after buying another GPU that a second card is not actually utilized unless you have crossfire(AMD) or SLI(intel) capabilities. No problem, I'm an idiot, let's move on...
It wasn't a complete loss since I was able to duo monitors and was able to dedicate my OBS streaming software strictly to one card which greatly helped with game performance WHILE streaming; here's where it gets a little funky:
I notice slight but very important rendering performance while gaming when my other graphics card is turned on and using my secondary monitor but what's weird is that the secondary monitor has absolutely nothing going on with it.... it's just ON. I couldn't find any answers as to why it was helping my game performance and until I do I'll just keep it running in the background.

Note: I did have a theory as to why this would happen: It might be handling the load of something in the background like the desktop rendering or other GPU dependent processes....which I haven't the foggiest as to what those may be.

And just to clarify: My main monitor is hooked up to the 1st GPU and my other monitor is hooked up to my 2nd GPU. Both monitors are on but only the Main monitor handles my games and I have NO SLI OR CROSSFIRE BRIDGE.

 

[Brantyn Gerik]

the final statement fully explains the performance improvement you see. another thing to note is that the r9-290 and 290x do not need a crossfire bridge.

if one card is not doing ALL the work, of course it will run slightly faster in that application, but no faster than it would if it were the only card and nothing else was running

 

[k1114]

But the 2nd gpu doesn't do anything as windows just shifts all work to the one hooked up to the primary monitor unless the software can specify. I run gpus not in sli/cf, did it in different configs over the years and never seen a difference. You could just check gpu usage on the 2nd gpu and see if it's doing anything to be sure.