Help on cooling idea

For a while Ive been wondering about making air cooling more efficient by seperating components. What I visioned was instead of a single rack unit that housed everything, seperate racks that were built for specific pieces, one for harddrives and controller, video cards, etc. The idea being that hotter components being isolated will no loner further heat others, and there would be more room for direct airflow, instead of the lets cram everything in front of everything and build heat of the more larger rack designs, also you could power everything with smaller seperate PSUs; most of the gold labels psus are a much smaller wattage rating. Nvidia has their external Quadroplex, and DigiDesign has their expansion chassis for their accel cards, who else has what? Anyone ever see anything like this? Or am I just missing something and someones got something that will bring a rack down to ambient temp while keeping the smaller space?

One of the issues to be handled is the length of signal lines. For purposes of ensuring reliable signal transmission at specified speeds, there are often limits on the lengths of cables to the hard drives; similarly, there are limits on the distances to the several PCI buses on the mobo (which we users can't change, anyway). Changing some of those will require a complete re-design of the basic components (e.g., the mobo) and / or some trade-off of performance.