R720xd: Questions about GPU and 2x2.5 flex bay

Now I know in the documentation it states that it does not support GPU's, however What if I am using a GPU that does not require a pci-e connector.
Or I am using an external power source for this GPU?

Will the machine still allow it to be used?

 Assuming yes to the above. Can I still configure the machine to only use the onboard VGA for boot (this will be a full GPU, not just a openCL/CUDA solution) that way I can assign it to a VM in esx?

Also, about the 2x2.5 flex bay/rear hot swap; Is it possible to plug/configure these drives as raid1 on the onboard controller  NOT the PERC H710(p) (see page 132, connector labeled #24)

http://downloads.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-r720xd_Owner's%20Manual_en-us.pdf