If I wanted to do the same, I would start inspiring my idea from some great threads here, example Aurora R8, Case Swap *COMPLETED*

Why do you want to migrate to a new case?

For Aurora R5 to 11, the power switch is wired to the led connector under the gpu x16 slot to the left of the blue cmos reset jumper.  You can rewire or some people get lazy and port the entire switch over. 

processor cooler*

Can I just get a new mother board? To by pass all this? I also have the r10 Ryzen addition and she is running hot want to buy a better processor and better power supply. 

New motherboard will simplify the transfer to a new case.

Another point to consider... my R8 had a molex cable from the PSU to the R8 motherboard 4pin connector. I could have got a new cable to power the 8pin slot on the new motherboard with the R8 PSU, but I felt it was best to not take risks, I got a new modular PSU for the new case/motherboard.

Very late to this party. 

Looking to do the same w/ my R10 (ryzen 5800x). Tried replacing stock fans w/ noctuas and sandwiching the AIO radiator but this case air flow is just abysmal with the rtx3080 in it. 

I'm probably going with just new case and a new B550 board. Is there any reason the dell 1000W PSU wouldn't play nice w/ a 3rd party mobo? 

I think it has been discussed in a recent thread, 6wires wired on the EPS 8pin connector, not compatible.

If you have a sandwich, it only improves CPU temperatures by a few degrees in my adventure, try putting one of those fans in the HDD upper front as cool air intake to the upper half of the case.

The PSU does not confirm to ATX 2.2 standards. Besides the EPS pin being an 8 pin connector with only 6 pins being wired up, you will also notice most cables that plug into the PSU have 6 wire connections instead of the 8 wire you would expect. 

24 pin MB power connector does not conform to the ATX standard, it is a custom pin layout.

Here's a guy who has done this with an R11. As you can see he explains it really well, and it's a struggle for sure:

https://forums.redflagdeals.com/dell-alienware-aurora-r11-r10-3080-3090-mod-thread-cooling-case-swap-2445451/

Also keep in mind not all modular cables are supplied with the PSU, like you would expect. They only supply what your system uses.

You can scrap that 1000 watt power supply because Dell has customized it to their own liking instead of following the worldwide standard that most other computer manufacturers follow. They simply don't want you to use these parts anywhere else and have customized multiple things to make your life difficult should you try to use these parts in another build.

Another thing they have done is customize the motherboard. The IO shield does not confirm to the ATX standard, and forms part of the chassis. While the MB itself mounting wise does confirm to the ATX standard, you will need to cut room in your new case for the IO shield.

If you are doing that you will have to mode the PSU over with it, because a "normal" PSU will not work with this board and might damage it.

If you are planning on moving the AIO liquid cooler over, the hoses are abnormally short. Customized for this case. Moving this over to another case might not be possible.

Fans form another issue, because the motherboard only accepts a few select aftermarket fans. Trying to start up with something else might result in an error message during boot.

There's also the custom power case switch, the custom USB MB connectors etc...

Personally I would strip the CPU and Video card from the Alienware and purchase all the other required components. It's just not worth the hassle dealing with all the customized parts and layouts and not worth smoking new components with all the customized cabling and pin layouts.

Unfortunate, but this is the way Dell wants it.

The biggest issue with the Dell power supply is the length of the cables, you will either need extensions or custom cables which will cost as much as a new power supply. 

For Intel, the back bracket is fixed to the Socket Backplate,  aftermarket cooler will not fit and you cannot use the bracket that comes with the aftermarket cooling solution. So you swap the socket backplate with a standard one. Standard socket backplate from any LGA 1156 to 1200 motherboard.

https://www.amazon.com/Intel-LGA1156-Back-Plate-1156BP/dp/B00NWOV2OO

https://www.amazon.com/Wraith-Cooler-Processor-AM4-Connector/dp/B07GKRR5WR/

AMD Wraith Prism LED RGB Cooler works very well

but i don't know about dell mounting

Coolers Depend on AMD or INTEL.

Note the AMD High end Air cooler does very well

I like the idea of moving the fan to the front but I feel like it's got nowhere to intake from. Like trying to breathe through a coffee stirrer. 

Could probably just blow it all up onto a test bench kinda deal like the master frame 700 without worrying too much about case compatibility or needing new mobo. It would look HIDEOUS but who cares

Thanks for the replies

Oh man that stinks with the PSU

I've done prior frankenstein builds on older dells and new PSUs wired up no problem. But now the connectors are proprietary? That's...cruel

So now I'm at needing case, mobo, PSU and I should be good. I'm being super cheap, I know, but I've found an acceptable workaround with the AIO radiator, as long as measurements are correct 

on the Pinout for the dell PSU is looks like they are using the exact same +5,-12, ETC lines. I would think you could just cut and splice them to ATX spec, But I am not sure.

Yes, you could. But the problem is you would not have the same current ratings.

Like for example the EPS 8 pin is rated to deliver 7 amps per line, for a total of 28 Amps.

Since the EPS 8 pin on the DELL PSU is wired as 3 lines, the total would be 21 Amps.

Sure, you could splice in the 2 extra wires and make it an 8 pin, but you would take a risk of overloading the PSU, overheating the wiring, even causing an electrical fire, since the set of wires you spliced in now have to carry 2 x 7 Amps = 14 Amps, which is past the AWG rating.

The proper way of making an EPS 8 pin would be to use a Y-splitter , 8 pin EPS to 2 Molex.

But the DELL PSU has no Molex connectors for that either...

http://www.playtool.com/pages/psuconnectors/connectors.html#eps8