XPS 8700, how to switch from/to Dell M3 backplate and cooler LGA115#

I have a motherboard LGA1155 with clear heatsink mounting holes

I have a dead XPS 8700 mobo with Dell M3 thread back plate and oem air cooler.

I found out I can loosen three Phillips screws of the ILM of cpu socket of 8700 and detach the Dell back plate.

do the same for the other LGA1155 ILM which has a smaller rectangular backplate fastened to ILM by three Torx 20 screws.

now move the Dell backplate and ILM to the otherboard.  fastened the ILM to Dell backplate via the three Phillips screws.  now the board can use Dell cooler.

another possible scenario: Dell motherboard has the M3 threaded backplate.  I want to change to clear mounting holes to install non-Dell heatsink such as Cooler Master.  By loosening the screws and switching backplate to the small rectangular one (removed from the aforementioned board), I can make the Dell to work with third party heatsink.