Fixed page width versus 100% page width

Which gets a higher CTR?

[mafew]

I'm redesigning a site of mine.

I initially wanted to make full use of the page's width, but then figured ads are going to be more prominent if the audience's vision is concentrated on a smaller area.

Has anyone run tests on how page width affects CTR?

[fischermx]

Longer than 125% is bad specially if you run the skycrappers format and get the ads out of the sight.

;)