I have a fanless Asus EAH3650 (ATI HD 3650) video card that has been powering two 1680x1050 monitors on my workstation (Q9650, X48, 8GB RAM, P182 case, Vista 64-bit) for the past 3 years.
I recently upgraded one of the monitors to a 1920x1200 model. Since then, I've noticed a slight lag when typing or selecting text in my favorite text editor (NoteTab) or in other apps like Excel on that monitor. The lag feels like the slight lag you feel when using remote desktop or typing in a terminal window for a remote system. The lag seems to be worse when the window is sized large. It seems to go away when I switch the graphics card from 32-bit to 16-bit color on that monitor or when I'm working on the smaller screen.
I'm thinking my graphics card may be a bit underpowered for 1920x1200 at 32-bit color but am not sure. Most people think about 3D performance when evaluating graphics cards but I'm more interested in 2D performance (editing code, typing in text windows, working in Photoshop).
I've already tried loading the latest ATI drivers and am still seeing the problem. Do I need a faster video card? If so, can anyone recommend a good fanless card that can support two 1920x1200 monitors without getting super hot? I'd eventually like to run three 1920x1200 monitors. I rarely do any gaming.
It's possible since the card is passive that it's heating up and lowering clocks so much that you get a little delay when trying to accelerate Aero. Can you check temps at all? Also your card is not underpowered for 1920x1200 @ 32bit unless clocks are lowered a ton. In fact any card from the last 10 years could probably do Aero just fine at those resolutions.