I have a pci-e 3.0 card and I have a pci-e 2.0 motherboard
it's rare to find 3.0 motherboards unless its intel ;-;
Maybe the cheaper ones, if you bite the bullet and pay more for an expensive Asus motherboard you'll get PCI 3.0.
My approach to building computers is apparently really unpopular.
I am more interested in spending money for a really nice, beautifully designed case and a solid motherboard and PSU. Its important to not cheap out on the RAM, and to stick to an Intel Core i5 processor or above.
However, I am more than happy to go with a cheaper graphics card so long as I get 40-60FPS at medium to high details on games. I feel this is an unpopular opinion to have, because most people get an AMD cpu and a cheaper mobo to factor in a high end card. I find it utter madness.
Imo the motherboard is the foundation of a good computer. Cheaper mobos will skimp out on special features, will perform less, and are more likely to die because of cheaper electrical components. They are also more likely to date because of not being on the cutting edge.
I am also against overdoing LED lighting, against people using SSD's unless they can practically budget it in (and only when requiring it for fast Windows performance, if you buy stacks of them for fun you are a moron).