The order is what is required for your specific model. I have seen no difference in the colors only the order of the pins. Note the Difference in this adapter. [IMAGE] [URL]     So if your fan is NON standard you may need to remove the pins and re order them to be correct.  The fans are not any different only the wire order. Dell started making all the wires black so you cannot tell.  its not documented and its not the same on all dells all models all years. [IMAGE]DELL VS INTEL FAN COLORS[IMAGE]DELL To Standard 4 pin adapter[IMAGE]Note The KEYWAY[IMAGE]Another ay to look at it  
Did Dell change its pinout order for the cpu fan header as it crossed from gen 4 to 5? i fried my 7040 fan and had a 9010 at work that was on its way out the door so i snagged the fan. I noticed that the 9010 fan connector order was BLUE BLACK RED YELLOW On the 7040/5040 fan connector, the order is  BLACK RED YELLOW BLUE So are just the cable colors different or are the motherboard pin functions in a different order? Any help appreciated. Ive seen alot of fan discussions but cant find much in the way of 7040 fan pinouts
Fan pin out order