Transplanting an XPS 8100 motherboard into a new case?

Your para 2 is going to be the problem because Dell use their own control panel which is not necessarily pin compatible with a generic case's leads. As you say the power switch is the main concern -- Dell computers are quite quiet but in a quiet room you'll hear it running so a power indicator may not be vital. The power switch only uses two wires so should be pretty easy to identify and improvise, especially as polarity of the wiring doesn't matter. Unless you Dell uses standard pin connectors at the motherboard end I would simply snip the power switch wire at the end nearest the case and wire it to the appropriate connector on the new case (best to solder and insulate or use a plastic and metal block-connector).

Have a hard look at the power supply because Dell have used non standard ones in the past and it may not fit the new case screw holes. It's tempting to change to a new PSU anyway because Dell are ungenerous with the wattage of the supplied unit.

I already upgraded the video card and the PSU to a 700 watt unit. The PSU in my computer is a standard ATX size unit.

What is para 2?

Hasn't anyone moved an XPS 8100 to a new case and figured out the pin assignments on the motherboard?

What is para 2?

The second paragraph/part of your original post.

I would leave the processor in because removing and replacing the heatsink can be difficult -- and if the tool you're using slips it could wreck the motherboard (I've done that).

Obviously remove any PCI/AGP cards and take out the coin battery -- you'll probably short it anyway if you touch any metal moving the board in and out so you'll have to restore the BIOS settings (simple on a Dell).

Just wanted to post that I did this last night- transplanted my dell studio xps 8100 motherboard with i7-860 into a new aftermarket case without any issues. It is a standard size mATX board. The only hiccup was the power switch, power led, and hdd led on connectors but dell has them bundled into one plug in the lower right hand corner of the mobo. The case had them individually so I just pulled out the power button module in my dell, figure out which wires were for what (switch, light, etc), determined their position in Dell's bundled connector and then just connected each individually to their respective pins. Works without a problem. It took me about 5 minutes to figure that out and the whole transplant took about 1.5 hours.

The ONLY thing I couldn't get to work was the reset switch on the case, which I don't really care about.

PS- In case anyone is wondering, I've replaced my PSU and the stock CPU cooler, but inside the new case, my temps have dropped a whopping 30-40C for both my CPU and GPU. The Dell XPS Studio 8100 case may be purty to look at, but functionally its a nightmare because its unbelievably cramped, even in its stock configuration, let alone if you decide to add/upgrade something.

Perfect timing. I had abandoned this idea but within the last month decided to try again. Which case did you end up using? Can you also explain how you figured out which wire was which in the bundle? Thanks.

I would guess that the machine was using a BTX motherboard - Docprego, check your model before you swap cases. BTX motherboards (used it dells now) are not compatible with ATX (common) cases.

i just bought a coolermaster haf 922 and im trying to move my xps 8100 into it.
i still cant get the power switch working nevermind all the LEDs.
i have tried tracing the power connectors with no luck. it still doesnt power on. is there something im missing???

if you remove the top casing you can see what color wires go into the switch. then you can traces those ires back to the bundle to see their positions. it didnt really work for me though...