I would have recommended the 8800 GTS (in my opinion, it's currently the best value out there price/performance wise), but there is no way that he could run it off of a 300W PSU. He'd need 450W, minimum.
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Thor:
Intel Core i7 4770K|ASUS Z87Pro|32GB DDR3 RAM|11GB EVGA GeForce RTX 2080Ti Black|256GB Crucial M4 SSD+2TB WD HDD|4X LG BD-RE|32" Acer Predator Z321QU 165Hz G-Sync (2540x1440)|Logitech Z-323 2.1 Sound|Win 10 Pro
Explorer (MSI GL63 8RE-629 Laptop):
Intel Core i7 8750H|16GB DDR4 RAM|6GB GeForce GTX 1060|128GB SSD+1TB HDD|15.6" Widescreen (1920x1080)|Logitech R-20 2.1 Sound|Win 10 Home
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