Here may be the solution to your problem.

In the top right corner of your screen there is a small window that allows you to make various changes to objects.  If you have your light selected, in that window you see "color" "softness" "spread" "falloff" and "power".   If you click on the little icon left of "falloff" you can now make various changes to that spotlight in the pop up window.  You are presented with two sliders,  "Intensity" and "quality boost".   Adjust first the "quality boost" slider all the way to the right, then adjust the intensity to you desire.  You may also want to play with the check box "show smoke or dust in light beam" option.  Hope this helps.