u have a few choices:
1. get a new GPU and be bottlenecked by the CPU
2. get a new rig but will cost u a lot
3. upgrade your dead platform + GPU (already at the end of life)
4. switch to intel counterpart and save some money on the RAM at very least
GPU really depends on your whole system, for the system u have now, i'd say it's already pretty balanced (old budget GPU + old budget CPU)...