The CPU, memory, and motherboard will be a massive bottleneck for that graphics card, they are all out dated for such a new graphics card.
So the GPU needs to downgrade right? What should it be?
Down grade the GPU or upgrade the other parts, those other parts are 7 years old now, the GPU is just a waste of money on that system.
It also states in your build that some parts are incompatible, the CPU doesnt work with that board without a bios update first, and to do that you would need a CPU that does work.
Do you have any preference on a System ? Intel / AMD ?
This is a tiny bit over budget, but this would also be a gaming machine, with 8gb of dual channel ram, would knock the socks off your system build for $11 more.