What black does do is absorb the whole color spectrum from sunlight.
Place a black object and a white object outside in the sun, wait an hour, and you will find that the black object is very hot, but the white object is only warm. This is because the black object absorbed all of the color spectrum, but the white object only absorbed the white part, or a fraction.
This is why in the winter dark color cars with melt the snow off faster in the sun than light color cars.
I wouldn't bother repainting the case. Besides, are the other parts of your case black on the inside?
not totaly black is also the best RADIATOR of heat aka black body radiation »en.wikipedia.org/wiki/Black_body this has more to do with why black gets hot then it not reflection light
