The internal cooling fans for Sun/Cobalt Raq3 and Sun/Cobalt Raq4 can be a nightmare to source.
The actual fans themselves are Sunon fans with the Sunon part Number KDE1235PFB1-8
For UK supplies of the fans, try Alan Walker at
www.thermaco.co.uk
Delivered by 1st Class post (usually overnight).
Update
Another piece of important information is that the Sunon KDE1235PFB1-8
fan, used on the Sun Cobalt products, will become obsolete during this
year(2005) and replaced by a new device, designed to meet the RoHS directive,
coming into effect in July 2006.
Thermaco will continue to supply the KDE1235PFB1-8 until stocks are
exhausted and then convert to the GM1235PFV1-8.GN. The new fan features
enhanced performance and lower power consumption.
Thanks to Stuart Read at Thermaco for the update.