can you tell me which mobo you are referring to?
As I typed above will the i9 Z390 cover all that I require?
basically i use a internal pcie wifi adapter, its called a: ASUS PCE-AC88 AC3100 Dual-Band Wi-Fi PCIe Adapter
I use this because it partners up with my Asus RT-AC88U Router, i get very good performance wirelessly hence why I prefer this to standard motherboard wifi
I also have a SoundBlaster ZXR and again this is key because of the headphone amp I use with my high end cans, 600ohm
Also the 1080ti, so right now I have 3 components that I use on my motherboards PCIE lanes
I will abandon my quest to go SLI, i will just have one card, and then upgrade to a RTX 2080ti in due course.
But the importance of 1 GPU 1 sound card one wifi adapter is key, additionally if this CPU can also handle a M.2 then that will seal the deal, i will order 1 z390 intel i9 and a motherboard that can cover all my components
immediately
Z390 will be able to accomodate all of the pcie expansion cards you have listed as long as you buy a board that has enough physical slots. For example, you couldnt use itx or matx.
The cpu has x16 pcie lanes which can usually be used in either x16 / x8 + x8 / x8 + x4 + x4 or another config as specified by the mobo manufacturer.
In addition to this the z390 chipset provides an additional pcie lanes which add more physical pcie slots to the motherboard.
In my pc i had a soundcard, gpu and m.2 drive and still had slots free if i needed them.
The drawback to having limited pcie lanes is that if you use the pcie bandwidth of the direct cpu connection for a gpu and another card, then you wont get the full x16 speed on the gpu slot. For anything below a 2080ti this is not an issue and is unlikely to be noticeable with a 2080ti but will have a small impact.
However if you put the m.2, wifi and soundcard on the chipset (if possible with the board you select) then the gpu will get the full x16 lanes and bandwidth from the cpu.
In any case, even if you select z390 and a 2080ti and it runs in a slot in x8 mode, it will still be a faster system than an equivalent x299 with gpu in an x16 slot, because the 9900k is so much faster for gaming than the x299 cpu options.
Anything that you put into a slot that uses the chipset pcie lanes will be communicating with the cpu via a x4 link from the chipset. This is because the chipset and cpu are linked by a connection that is effectively pcie 3.0 x4 bandwidth. This will not be noticable unless you are considering several m.2 drives in raid, however it is worth keeping in mind.
If you decide you want a mobo with the plx chip which provides additional pcie lanes (not really required) then your options are the Asus WS Pro z390 board, or the Supermicro C9Z390-PGW. But be prepared to pay for it.
You could still wait for ryzen 3000 series which is likely to offer more pcie lanes from the cpu (20 iirc vs 16 of intel at least) and possibly even pcie 4.0 vs the current pcie 3.0
I hope that helps. I know its a lot of info but the short answer is that for gaming with the config you have specified z390 will be more than adequate and will be the faster platform than x299 due to the cpu.
