What size monitor is good for todays game's? I was looking at 23" or 24" at a native resolution of 1920X1080. I didn't know if that size with that resolution would cause any problems with bottlenecking or bad FPS performance in games. For the people who built computers for gaming what size monitor are you using?
The size is not an issue. The issue lies in the resolution. Regardless of size, 1920x1080 will require the same number of pixels. Whether it's 21" or 27"....the graphics card is still doing the same amount of work to produce the image.
Size has nothing to do with performance. It is the resolution that counts. Whether you are playing games with a 21.5" 1920x1080 resolution monitor or a 62" 1920x1080 resolution HDTV, the performance will be the same.
the biggest you can afford and fit on your desk. As for resolution vs performance, yes the higher the resolution, the lower performance you will get. if you get a 1080p monitor, the minimum graphics cards you should be looking at are the HD6850 or the nvidia gtx460.
You should consider your actual setup. Even a 23" monitor is pretty big, and you have to sit far enough away from it so that you can take in the whole screen at once. That'll also make sure you don't see the individual pixels (regardless of how good a monitor is, if you're close enough, it will look bad).
You can use a calculator like this, though it's designed for home theater setups, but will give you a sense of what you'd want for using the monitor for watching movies, and for some gaming (might want to be closer for online FPS):