The specification of Asrock B75M-R2 motherboard mentions it has PCI slot....Moreover the GTX 660 also requires a PCI 3.0 slot which the motherboard has.
You can check your motherboard specs in this site: http://www.asrock.com/mb/Intel/B75M%20R2.0/?cat=Specifications
So you should be fine ...
JUST BE SURE YOU HAVE A GOOD PSU 450 WATT PREFERABLY AND A 6-PIN CONNECTOR FROM PSU FOR THE GPU.
It has a PCIe 3.0 x16 slot, the GTX 660 needs a PCIe 2.0 x16 or higher slot, it will work fine. What is the rest of your system? There might be another incompatibilty somewhere.
The specification of Asrock B75M-R2 motherboard mentions it has PCI slot....Moreover the GTX 660 also requires a PCI 3.0 slot which the motherboard has.
You can check your motherboard specs in this site: http://www.asrock.com/mb/Intel/B75M%20R2.0/?cat=Specifications
So you should be fine ...
JUST BE SURE YOU HAVE A GOOD PSU 450 WATT PREFERABLY AND A 6-PIN CONNECTOR FROM PSU FOR THE GPU.