Both of these power supplies are identical except for the specifications and connections. The 650W model is geared towards mid to high-end rigs and the 850W model is best suited high-end to hardcore computer systems. The NorthQ Black Magic Flex 650W & 850W Power Supplies offer clean efficient power, comes with a very quiet 135mm fan. They are both very compact and will fit in any ATX case on the market, including most HTPC and SFF cases. These PSUs has lots of leads, the main motherboards leads are hardwired into the PSU, but there rest modular sleek looking flex cables. As the name suggests, the cables are super flexible, which allows them to bend around almost anything. I love flex cables! Watch the video to find out more.