If i want to cool my computer, e.g. when running Folding@Home on the two separate GPUs in my graphics card i just take off the side of the case and have a big fat fan blowing on it. Without the fan it gets to 105°C which is the limit but with case off and fan on it gets down to 80 maybe 90°C tops.
Liquid cooling is just for people who are hard core gamers or similer and need it for things already mentioned like overclocking