I bought 2 refurbished pc's and one unit was missing the rear case fan all together. I called and got a case fan sent. Once installed, I still got an error on the case fan. I believe there is an issue with the mother board because how could the unit be refurbished and checked without a case fan. The error pops up on any restart. I called customer service and was told that they didn't have any replacement units and that I needed to order from a different supplier. The company should have replaced this with an upgrade but instead told me to go elsewhere.