Ok so it's definitely an upgrade.
Right now I would have to say the PSU isn't able to give it enough juice. I think it recommends a 500W PSU, which you won't actually need that much but it kind of covers it's ass if you buy a low quality one that doesn't have a lot of amperage on the 12V rail. I've seen it happen several times that the card can't get enough power so the speed just isn't there.
If you get a Corsair, Antec, Seasonic PSU you could make do with a 450W model for sure, probably a 400W would work.
Also make sure you remove the Nvidia drivers.
Im goin to build a rig from scratch and use the GC in it. so ty for the info