Vista - Graphic Card and BIG screen

I wonder if the size of the screen\monitor affect\stress the graphic card.
I have ati radeon 3870x2 connected with lcd samsung 40'' tv.

This main problem with driving a large monitor is getting a card with sufficient grunt to do it. I am pretty sure your cards do. I guess they may be working harder, the easiest way to tell is by monitoring temps. If they are stable the you shouldn't have any worries

Norm

It depends on what your doing. The real stress on the card would be running 3D intensive apps (games for example) as close as possible to your displays 'native' resolution.

If your TV is a 1366x768 (720p) panel, then your native resolution is 1366x768. If it's a 1920x1080 (1080p / i) panel, then the native res would be 1920x1080. So if your trying to get as close as possible to your native resoultioun, running at 1920x1080 will tax the video card more than 1368x768. The same goes for any display.

However, for normal desktop usgae, it barely effects the card at all regardless what res it's set at. Your 3870x2 should handle the 40' no probs for normal desktop usage.

Running at a lower than native resolution just affects the image quality under low load circumstances.

Be a different story with a 30" LCD monitor with a 2560x1600 native.