When running Techtool Pro on my MacPro (2009) it shows a bad RAID drive pair and a failed "boostA fan". I believe this is the fan in the processor enclosure. Is this easy to replace and is there a store which sells the replacement part? Apple apparently no longer ships it. Also, what is the danger if the fan is not replaced?
They are within the CPU heatsink assembly. See:
http://pindelski.org/Photography/2013/07/06/mac-pro-2009-part-x/
This manual gives good instructions for the 2009 MP.
http://tim.id.au/laptops/apple/macpro/macpro_early2009.pdf
A failed boost fan will result in higher CPU temperatures. If they get too high that can cause problems like kernel panics
Fan replacement
