Are you thinking of a laptop? If so, i wouldn't recommend it, as laptop macs cool through the "top". It would probably damage your laptop permanently...
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- iMac g5 2ghz, 1.5gb ram.
- eMac 1ghz (clocked at 1.27): 1gb RAM, Dual Layer Pioneer DVD +/- RW, 80 gb HD, 160 & 250 external Lacie FW HD´s. And modified cooling.
- iMac 600 mhz
- b&w in atx case, with sata drives :p
- PowerMac g3 b/w - with atx psu
- PowerBook G3 Wallstreet