XPS 8930, upgrades for everything

@zekebeast    I have quite a few upgrades planned for the future. 

I will take a shot at a few items . . . first, whenever possible, link components to the manufacture's web site, not to some dweeb selling on Amazon with limited, possibly incorrect information.

First of all: RAM - RAM can be hit or miss due to all of the Dell proprietary nonsense, but Crucial is a good source because of their guarantee . . . Crucial . . . not Amazon.

Secondly: Power Supply - the PSU you linked is 160 mm long (if the Amazon info is correct). This consumes a lot of cable management space for the fully modular PSUs. Consider getting a PSU with these dimensions; 140 mm (L) x 150 mm (W) x 86 mm (H) . . . and also consider 850 watt, the incremental cost is usually small  for example  which will look like this

Next: Case - if you are getting a new case, you are effectively doing a new build, salvaging the components from your XPS 8930 the transfer easily. Therefore, you should also consider a new motherboard, as the Dell OEM the rear I/O creates problems, as does the proprietary electronics in the front I/O.

Next: Graphics Card - the RTX 3070 Founders Edition graphics card will work with the XPS 8930 motherboard, and will also fit in the case without modification. The aforementioned PSU upgrade will be necessary.

Next: SSD - lose the Optane

Finally: CPU and CPU Cooler - i9-9900K is a great CPU and will work with the XPS 8930 motherboard. You are correct that additional cooling mitigation will be required. With regard to the  air cooler to which you linked . . . I do not think 165mm height will fit in the XPS 8930 with the swingout PSU. I believe your best option is the blower style fan/heatsink that came with the "K" processors. This unit exhausts air up through a fin stack and directly out the top exhaust fan. Looks like this  You should also make sure you have a 120mm top exhaust fan, and add the 120mm lower front intake fan. The VRM heatsink would also be a good add if you do not already have that in place.

@zekebeast In my opinion, given all the upgrades you are planning, it does not make a lot of economic sense to upgrade your XPS 8930. The only thing you are saving is the motherboard, but the Dell motherboard is an issue because of its propriety interfaces and lack of overclocking capabilities if you are considering a K processor. With a motherboard upgrade, you may not be able to use your existing memory and you will probably need a new copy of Windows 10. 

@Vic384 So are you suggesting that I should just build a new PC?

@Anonymous So first of all, I should buy components directly from the companies and not Amazon correct? Thank you for all your research but after reading @Vic384 and your response I think I might just build a new computer. However, if I just upgrade the RAM, PSU, and GPU, do you think there would be enough cooling in the default XPS 8930 case?

@zekebeast If you need all the upgrades that you listed, then yes it would make more sense to combine them all in a new PC. You are upgrading all the high-cost items except the motherboard which is problematic given its proprietary nature and major lack of overclocking capability. 

@Vic384 I see. Thank you!

@zekebeast    So first of all, I should buy components directly from the companies and not Amazon correct? 

No . . . that is not what I meant at all. What I meant was that when you are researching the components for your build, the manufacture's web site will provide the best and most complete information. Once you use that information and make a decision about any particular component to include in your build . . buy it where ever you can get the best deal.

I have the same problem