i7 920 is also to old, if you want a new graphics card I would not aim to high. A 570 or 1050Ti would be a big upgrade right now.
This is however the last upgrade for this PC because you are going to have to sell out and get a new CPU/Motherboard and modern Ram at some point, you are going to be CPU Bottlenecked in many games if you buy a much higher graphics card.
The 2500k and 2600k are still acceptable but the first generation of i5/i7 processors is at its limit for some time.
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