Gtx 650

I'm looking to get a gtx 650, but will it work in my pc?

Also it says this:
Supplementary Power Connectors 6-pin X1

^ Do I get the 6 pin connector or do i need one?

here is the product

Palit GeForce GTX 650 (1GB GDDR5/PCI Express 3.0/1058MHz/5000MHz) : Nvidia Graphics Card : Maplin Electronics


Also, my PSU is 300w, is that enough for this?