One video card per monitor (dualboxing)

[Payne]

My Situation
I have been successfully dualboxing WoW with a Geforce GTX 260 graphics card. I recently purchased a GTX 470 to replace it. It occurred to me that I now have two usable graphics cards, either of which can easily handle an instance of WoW.

Is it possible to have both graphics cards installed at the same time (I have the slots on my motherboard), and to have each card running one monitor. So basically the 470 powering my primary display with my main copy of WoW, and the 260 powering my secondary display with my second copy of WoW?

Thanks very much for any info.

[Ualaa]

In general, you're better off with multiple monitors plugged into the same video card. I'd plug them both into the GTX 470.

You can still have both cards in the system, and it will run better than either card alone.

With XP you really slows down from any PiP switch, even across the same video card; with Vista/Win7, you can swap which region is on which monitor (without FPS loss) as long as all your monitors are on the same video card.

With any operating system, if you have your main on monitor A and your slaves on monitor B, and each of the monitors is plugged into a separate video card, if you PiP switch so one of the slaves is now on the main monitor and the previous master is now on the monitor with the other slaves, that's a FPS hit.

If you're never going to PiP switch between regions/characters, then each monitor on its own card is a gain, as long as you set each monitor to render off of the corresponding video card.

[Payne]

Thanks very much.

Forgot to mention that I'm running Vista 32-bit (likely Windows 7 64-bit after Christmas).

I would never swap which instance of the game is running on a particular monitor (so always WoW1 running on primary, and WoW2 running on secondary). The only thing I would do is change which monitor I'm focusing on, by mousing over from my primary monitor to my secondary monitor occasionally (for looting, etc). If I read you correctly, that should be a performance gain?

as long as you set each monitor to render off of the corresponding video card.

Is that a setting in Windows, or a setting in my dual-boxing software (currently Keyclone).

Thanks again.

[Ualaa]

It used to only be possible with IS Boxer.
However, any software can do that now via a video setting, inside of Warcraft (this is the recommended method with IS Boxer too now). You can set which monitor to render a given client on.

[Tim]

Hey there,

The big issue isn't so much which card renders, or which monitor is assigned to a faster card. The issue is the transferring of GPU memory space from CardA to CardB.

So in Windows Vista as well as 7, if you move a prgram (eg, WoW) which has a memory footprint in the GPU, it first has to go through a copy phase. For programs like web browsers, mine sweeper, flash videos, etc., this happens pretty much instantly.

However, WoW itself can have a footprint around 400M (or more in Cata) in your GPU's memory, and copying that 400M between GPUs can sometimes take 1-4 seconds, depending on how many frame grabber type applications you have running (eg, stream capture, FRAPs, Windows Aero, Windows Core UXSMS) which is the reason why you would see lag.

So your best bet is to put all your WoWs on 1 video card, or better yet, 1 SLI group (SLI groups automatically synchronize memory). Check with Nvidia's site, a lot of their cards will be SLI-able even if they aren't the same exact card. It might be limited to 2xx, 4xx, type of things, but not 100% sure.