I have used a g10 on an r9 290 with a reference PCB. From memory I believe the bracket mounted up to the normal cooler holes around the GPU core.
So looking at the toxic PCB, which is not reference it should still mount up. As the die sizes should be the same and hole spacing similar.
I would see if your local store will let you return it just incase you can't fit it.
Make sure you get some heatsinks for the memory and VRm's as well 😉
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