Yeah they haven't been cleaned for a long time. Some have been sitting in dirty work sites for to long.
Best way to clean them is with an air compressor or a can of compressed air, you only need to take the cover off and give them a good blow out. Then you should put new thermal paste on the CPU just to make sure. Chances are if you have a computer that dirty then the thermal paste could use a change.
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Also all of these were still in working order!