@DayRider, They aren't paid, and if they were and their benchmarks were half the actual performance like you are suggesting, they would have zero credibility among the PC community and that obviously isn't the case.
Something is clearly wrong with your configuration or with the actual hardware itself, because you are getting 1440 performance on 1080 (should double check your resolution settings). Reinstall your drivers, check and make sure clockspeed is fine with GPUID, double check all of your game settings, use a different benchmark program or reinstall the one you currently have as it could not be installed properly, etc.
If your using a founder's edition, there's a decent chance there is a problem with it, because reference cards are notorious for not being quality controlled. Your motherboard is also notorious for not playing well with graphics cards or really anything for that matter. I'd check those two first, and work from there.
@Ellas, Depends on what resolution you are play at. For 1080, it'll be fine. For 1440, it'll still be fine unless you need 60 FPS minimum. For 4K you'll more than likely either have to upgrade, which you should want to do anyways, or get a second one for SLI.