[Discussion] Dell 7020 - Sleep routing?

[nicksoph]

Hello 
I am after some guidance about fixing sleep issues with Dell 7020's  when used with OSX.
The 7020 comes with Haswell CPU's and HD 4600 graphics. The machines make excellent hackintoshes as long as there is not an additional GPU when they fail to sleep properly. The standard HD 4600 GPU settings do not work and the config that does work uses settings for the HD 5200 GPU which works except for waking the machine when the BIOS setting for Enabling Legacy Option ROMS must be enabled if sleep is to work without an additional GPU, which seems strange because there are no Legacy Option ROMs. I have tried to discover what this setting does and how it effects the sleep process but I do not understand enough to be able to understand the sleep routing process. Looking at section 4.6 of the ACPI specification - https://uefi.org/sites/default/files/res...PI_6.0.pdf 
seems to show two routes to getting the machine waking from sleep - Legacy/UEFI -  and I think that OSX is somehow only waking the machine if the Legacy option is selected.

I am hoping someone can give me some general advice to help solve this issue but in particular I would like to know;
What do I need to understand or read about to understand the process?
Is there a way to get the build to use the standard 4600 config?

Many thanks in advance.
nick