Drop in FPS when using two displays/two GPU

[WB4CS]

Recently built a new gaming PC. Motherboard has onboard Intel HD graphics and also installed an Nvidia GeForce GTX 770 discrete GPU.

With one monitor hooked up to the GTX 770, I was getting about 110 FPS in WoW. When I hooked up my second monitor to the GTX 770 (as expected) the FPS dropped down to around 60-80 FPS.

My motherboard supports the use of both onboard and discrete graphics at the same time. I've enabled that setting, and have my primary monitor connected to the GTX 770, and the secondary monitor to the DVI output from the motherboard (Intel HD Graphics.) WoW is configured to display on the primary monitor using the GTX 770. I've confirmed in Windows 7 display properties that monitor 1 is using the GTX 770 and monitor 2 is using the Intel HD GPU.

I'm still seeing a reduction in FPS while playing WoW to around 60-80 FPS. If I disconnect the second monitor completely I return to the 100+ FPS.

Since both monitors are 60hz displays, it really doesn't matter if the FPS is above 60, as long as it remains around 60. Again, I expected a drop in FPS when using 2 displays on the same GPU, but when each display is being driven by a different GPU, I would imagine that the discrete GPU wouldn't see a drop in FPS since that the processing/output of the second monitor is being offloaded to the onboard GPU.

So I'm not really having an "issue", but more curious is this is a normal behavior. I figured this would be a good learning experience since it's been about 10 years since I've built a gaming PC.

Thanks!

 

[Shadowblade2652]

Is the game running on both, or just on one and using the second one as an auxiliary monitor?

 

[Dawis67_AE]

If the game is running both screens, then everything is as it should. FPS drops the more screens you add because the GPU got more space to render. Also a huge factor is Video Ram. More you have, the more screens you can run at same time.

But if you use the second screen for example for internet browsing and only one screen on the game, then its a bit weird.

 

[WB4CS]

Game is running only on display 1 (GTX 770.)

I agree, it is a little strange. Now one thing I have not considered is that my initial tests with one display was when I first began the game, in an area that's not as graphics intense as where I've progressed to now. I suppose it's possible that if I returned to the beginning area of the game I might see the FPS go up. I'll test that theory out today when I get home.