Precision 3660 got 500W having issues new bigger BUT HOW?

I think at this point both me, my tech friend and the dell support team members working on my service issue have boiled it down to not enough power? Right now the machine has a 500W PSU in it. And I have these in my system and periphreals plugged in, 1 NViDiA RTX 2080 SUPER GPU, 7 Hdd's some being nvme, 1 is a spinning drive and i have 2 that are external usb3.0 ones. I also have 2 sticks of ram right now and plugged in are Ableton Push 2, Akai MPK mini mk2, Presonus ATOM, Elgato Stream Deck, Logitech Brio, logitech G512 RGB keyboard and a Presonus Studio 1810c audio interface (which has its own power) and I would need enough for atleast that stuff and also I want to in the future upgrade the GPU to somewhere near an RTX 4080 or 90 depending on if I can get one slimmer than taking up 3 slots and probably 2 more sticks of 16gb ram.

So I decided i need to get a new PSU the 750 W but perhaps i need the 1000W, im not sure that detail and maybe you guys can help tell me if the 750W is good enough. So I called DELL Sales and they said they dont have any of the 750W nor the 1000W psu's available, atleast for right now, ill keep calling every 2 weeks to check back. But until then If i can just buy my own after market or some other name brand psu's to use instead in my system WHAT exactly do i need to buy? Please someone just give me a link to something anything i can get online anywhere. I tried to get the tech support dell guy to give me anything that he can recommend but was told he didn't want to be biased and tell me what to get. I was just having a hard time getting the information i need from him like what do i make sure the PSU has that I get if i gotta search for one myself. I want to be sure it has all i need on it and will fit. I have right now that metal cage with the black plastic insert on top of it installed but I dont have any clue what exactly that thing is used for. Anyone able to help me in getting a proper power supply that will handle all i have and possible plan to upgrade ? Or am I in the wrong ballpark and maybe something else is happening with my system, im like 90% sure it is power. Also when i try to boot up, i have 3 usb HUB's plugged in and it will fail booting almost everytime unless i wait forever and it keeps shutting down and coming back on sometimes it finally makes it to windows but when i unplug the 3 hubs i can get it to boot the first time so that there kinda tells me power along with some of the event id's ive found.

Thank you in advance for any help you can give me for this issue!