Area 51 upgrade options.

Hi all. Question about upgrading an Area 51 R5.

1. If I wanted to upgrade from an 850 watt power supply to the 1500 watt, that is just a straight swap correct? Take out the Dell 850 and put in the Dell 1500?

2. I know Dell released a bios update that made the R5 compatible with the 9th Gen CPU's so If I had a 7th Gen i7-7800x and wanted to upgrade to the 9th Gen i7-9800x, does it have to be an OEM Dell CPU purchased from Dell or can it just be a normal Intel i7-9800x purchased from Amazon or wherever? It's not clear as it stated something along the lines of OEM approved.

See here:
https://www.dell.com/community/Alie...Gen9-CPU-Upgrade-Support-R4-NONE/td-p/7235970

3. kind of the same question with GPU's. If I wanted to add a 2nd 1080ti for instance, does it have to be from Dell or would any other 1 work fine?

I am selling my AW18 and looking at a few refurbished Area 51 R5's with different configurations but have concerns about the above and it's surprising how hard it is to find answers about the Area 51, especially the R5. In addition, if the parts such as the CPU have to be from Dell, it's even more of a problem because it doesn't look like Dell even sells any CPU's other than the xeon ones now. Anyway, Any help would be appreciated.