You have not described the brand and model of power supply to support graphics cards.You havenot stated your computer case is full width for ATX height cards and double slot for card thickness.
There are worthwhile used cards from ebay sellers. However, in new cards
Your i7-4790K is Intel HD 4600 graphics.
EVGA 02G-P4-6150-KR GTX 1050 2GB is available at $110 after mail-in rebate from either B+H Photo or Newegg.
The GTX 1050 is under 75 watts and does not require a PCIe 6 pin power connector from the power supply.
GTX 1050 ranks at #79 or 80 where lower rank is better
Your current is at about #422
Your performance should be 5 to 8 times better. That is not 50 to 80%, that is 400% to 700% improvement in gaming performance.
You can certainly go more expensive cards, but you need to assure that the card fits and power supply is adequate.
$180 gets a low profile, if needed, GTX 1050 TI
There are lower cost 4GB of graphics memory GTX 1050 TI cards of standard height.
It's a 20 to 40% improvement over the GTX 1050 depending upon the game.
RX 460 and RX 470 are last year's cards and require a better power supply.
GTX 1050 vs RX 470
You can see an RX 470 is much stronger, but often bought used now. It even beats a GTX 1050 TI
An RX 570 is available for under $200
GTX 1060 6GB is about $250
You need at least a good 500 watt power supply with 6 or 8 pin pcie power connect.
Does your system accept a standard ATX power supply?
That should be $40 to $50 more plus the labor to change it.