So I had an RTX 2080 super that I got in early 2020, I think. I got an Asus z390 e motherboard for it with it and this is what the seller recommended so I got it but now my RTX card is dead so I'm planning to upgrade to an RX 6800xt but while checking the specs I found that its interface is Pcie 4.0 and I believe my mobo's interface is Pcie 3.0, I want to know if the RX card will work with my Mobo or will I need to upgrade my Mobo for the card?
Yes, it will work fine.
Yup! The beauty of PCIe is devices and the slots are cross and backward-compatible. You can plug in a newer device in an older place and vice versa.
However, using a 4.0 into a 3.0 slot may have bottlenecks as the card will utilize the 3.0 speeds, so you may sacrifice a little bit of performance.
I saw it will have a bottle neck of like few frames on some games so I think it shouldn't be any issue for, thanks alot for your helping.
It'll run, but PCIe 3.0 will slow things down.
Besides, you want to ditch that Intel Mobo/CPU for AMD. Get yourself an AM4 B550/X570 board on the cheap, stuff a 5800X3D in there (because they're at incredibly good prices right now) some DDR4 (3200CL16 is good, 3600CL18 is good, 3600CL16 is better... I think. Those are all the "sweet spot" kits for AM4 as best as I can recall) and you're gonna have a powerhouse rig for a couple of years. Or, you can spend some more and go AM5/DDR5 and be good to go even longer.
I actually have the Budget for only GPU and I think I'm stuck on z390. Thanks alot for your response, it was really helpful.