Jarsve
I've been using GTX660 and now GTX960. You don't need a top of the line card. But the newer the better., but without a new motherboard you don't get all out of your card ass you want. The PCIe standard is getting better every year and an old motherboard can only give the graphic card that it has of PCIe bandwidth. But it will work, just not as good as it was made for.

 Pricey cards use more power consumption. For a DAW like a GT240 works fine for a DAW.  Some new cards won't work on older boards. My 750ti would work on an older AMD board that only fits Phenoms IIs.  My 9800GT works fine on my recent AMD 970 board.  They are not plug and play like they use to.

GTX 660 is what I'm using. That or newer is fine with Windows 10

OP has long since disappeared...

I am using an nVidia GTX 980, but that's because I play games. You probably don't want to buy something that high end as it is pricey. It works very well though, and I'd imagine their lower end 900 series do as well, though that is still overkill for a DAW.

Radeon 5450. Drivers were recently updated for this one.