Fog on screen lags me out

I'm running six twos on a single computer with a 4870x2 graphics card feeding two monitors.

Whenever a foggy effect is displayed, my FPS drops to around 10 frames per minute. The effects I have seen that cause this are:

six rune keepers all put the hot on themselves
barrowland when the barrow candle puts the red shadow damage ring around you
great barrows where the worms explode and leave the green disease fog you have to get out of before it kills you
and to a lesser extent when the noxious barrow-wights die and leave the green fog

How do everyone else handle this? I'm thinking about adding a second graphics card, but the 4870x2 has dual GPUs, so I don't think it is going to fix my problems.

[lax]

Have you checked to make sure that the 2nd GPU on the 4870x2 is really in use?

Usually when people have multiple GPUs I recommend using them to power different windows on different monitors, and this way you have control over the load balance. Usually with SLI/Crossfire it doesn't work in windowed mode (one of them is supposed to now) and used to contribute to stability problems (possibly fixed by now, this started when SLI first came out)

Have you checked to make sure that the 2nd GPU on the 4870x2 is really in use?

Thanks for the tip, the 2nd GPU wasn't running, and to compound matters, the first GPU isn't being clocked at 3d speeds.

I had this all sorted out with WoW and WinXP, and didn't think about it when I upgraded to Win 7/64 so I could run six LoTRO clients (6 LoTRO requires about 7.5GB of memory) Based on web info, ATI doesn't think the second GPU needs to help out when in windowed mode.

I switched to a GTX 295 (and an 850W power supply) and everything seems to be working now. Now I need to turn up the graphics and see where it falls off the cliff.

The fog thing could be an ATI problem, I have it too even when running 1 instance of the game in fullscreen and I have 2 4890's