Firstly, the dispersion of artifacts isn’t consistant with an unedited image:

Also, within a given area that is unedited and consistent, a single macroblock type will be used. If the macroblock type changes, it indicates editing of the image.  Like so:

But the most damning evidence comes from Dave himself, who noticed that the Mini DisplayPort and Mini DVI aren’t lined up with where the motherboard is.  While Apple could have lifted the ports, that kind of setup weakens the joints.  Would Apple risk this type of behavior on the back of a consumer level machine – on the monitor port, the one which will likely incur the biggest load? Probably not.  They stick with the most conservative, reliable hardware designs following strict rules, which is most of what Unibody is about.  Fewer parts, more rigidity. So, unless Apple has decided to use a mini-DVI and DisplayPort socket that break a steadfast rule of reliability in design, it’s a fake. …Plus it is on a IKEA faux wood vinyl laminate floor.