Issue with Multiboxing WOW with second video card

I'll begin with saying sorry if this has already been posted I couldn't seem to find it so here it goes.

I recently installed a second video card ATI Radeon HD 3800 Series 512MB. Prior to installing the card I was able to have two monitors multibox up to 5 or 6 characters with no lag with my Radeon X1600/X1650 Series 512MB. I now have three monitors set up and Since installing the second card - I can still multibox but even with only two characters open I'm experiencing major lag. Could it be the second video card is conflicting with my original one? Possible Driver issue? Any Fix?

Any thoughts would be appreciated,
Thanks


My Hardware

"Computer"

"Operating System"

O/S: Windows Vista Ultimate 64 bit
ACPI x64-based
Drive Version: 6.0.6000.16407

"Mother Board"
Board:ASUS A8N32-SLI DELUXE

"Video Cards"

Card: ATI Radeon HD 3800 Series 512MB
Driver Version: 8.501.0.0

Radeon X1600/X1650 Series 512MB
Driver Version: 8.501.0.0

"Processor"

Processor AMD Athlon(TM) 64 X2 Dual-Core Processor 3800+
Driver Version: 6.0.6000.16386

"RAM"

4 GB Kingston

There are a few threads on this. They'll answer it in more detail, but in brief: all instances are rendered on the primary display adapter then copied elsewhere, so there is more work involved instead of less.

When you're lagging, take a look at your disk i/o lights. Adding another videocard eats away at your physical address space, but since you're running 64-bit Vista, this shouldn't be an issue. Since you've just installed a new videocard, I imagine the game has reset your /console maxfpsbk and /console maxfps settings. You may want to adjust them.

Also, running 5-6 instances of the game on a dual core 3800+ is going to be an issue for you.

I have an ASUS A8N32-SLI DELUXE w/ a 4200+. I had lots of problems getting this to work on Vista since they want to update your drivers for you. I don't know about you, but I use the nVidia raid controller and every time that bastard auto-update receives the nVidia SATA/Raid driver update, my computer no longer boots. Make sure that your system can see all 4 GB of RAM, and that you're not using the Physical Address Extensions (PAE).

Nvidia GTX260 and 8800GT, 5 box, expected FPS?