That CPU will not work in that ASUS MB. The 9th gen CPU is a socket 1151 while the MB is socket 1200 and will only work with 10th and 11th gen CPUs. If you want to stick with ASUS then you need a MB such as these available at Amazon for example.

Not going to work. When purchasing a motherboard, always check the supported CPU and Memory. For memory typically almost anything will work on a retail motherboard.

For CPU, only the listed CPU's are supported. The 9600K is not on the list. Supported CPU list 

Depending on the size and configuration of your new case you may need a new PSU or possibly cable extensions. Some of the OEM cables are quite short.

Oops I copied/pasted the wrong one.  I actually bought this...

ASUS Prime Z390-P LGA 1151 (300 Series) Intel Z390 SATA 6Gb/s ATX Intel Motherboard for Cryptocurrency Mining (BTC) with Above 4G Decoding, 6 x PCIe Slot and USB 3.1 Gen2

That will work, as long as the correct BIOS is present. It needs to be at least BIOS version 2203.

That motherboard does not have a BIOS flashback button, so you have to make sure it contains BIOS version 2203 or higher, or the system will not recognize the CPU.

CPU support table 

Hmmm is there a way to confirm what bios it was shipped with?

looks like it should be ok

Actually I misread and just realized that was a 9th gen cpu.   I emailed the seller on Newegg to ask them what bios version ships with the mobo.   Not entirely sure how to confirm that otherwise 

That is one of the issues these days if you don't have a BIOS flashback button to update the BIOS should you need to.

Sometimes if you get older stock, they come with older BIOS versions....

Yeah guess I will just have to check on the physcial mobo itself when it arrives.  Ugh...frustrating.  I am tempted to just buy a newer mobo and a new cpu at this point.  Just frustrating cause before the mobo was borked the i7 9600k was running just fine for my needs still

Most of the mobos that will work with this cpu are fairly old now and tough to find at a reasonable price it seems.  I have seen used and/or refurb mobos but I am somewhat leery of those (not sure if thats a valid concern on my part).  

Just figured I would update this.  New motherboard worked but I needed to get a new psu as well because the cables on the alienware psu were too short.  So new case, mobo and psu were required to salvage things.  Getting the aio to work with the new motherboard was a bit tricky but with some patience and finesse I managed to get it on and working.

All in all was worth it for  me I think since the 9600k and 2060 were still performing just fine for my needs

Drop some photos of your build if you don't mind sharing.

Gotta clean up some wires and whatnot still but should look fairly decent once I get it tidied up

Quick one I took.  Certainly not the flashiest but tbh with no build experience I was sorta just happy it ran  

Nice work! . . . and now you have some build experience.