From this video 7020 SFF tear down you can see 7020 case has cpu heatsink directly screwed onto case, so when you transplant motherboard to new case you need to buy your own heatsink back plate, otherwise you can not mount the heatsink. also looks like SFF back plate is an integral part of chassis. Unless you find a plate that matches back IO exactly, you won’t have a plate any more.  Just to let you know.  
I have a 790 MT case that I would like to put a newer(3010 or even newer) SFF or USFF mobo/cpu into so I can upgrade. I want the MT for the ease of putting additional PCI cards into it. I have an aftermarket PSU also that works with the desktop and MT mobo, but I would like to know if the SFF and USFF use a different PSU setup. Thanks in advance!
Can I put a SFF/USFF mobo/cpu into a MT dell case?