Thanks I will run prime95 but I have to do some clean wiring but how to fix cpu_fan error on start-up?
Is the CPU Fan error related to low speed? If yes, then I also faced it when I installed CM Hyper 212 Evo in my i5-2500K + Asus P8Z68 Deluxe configuration.
Nothing really to worry about. The stock cooler ran at high rpm speed even at low temperatures. Hyper 212 Evo's fan used to run at low speed because it didn't think that the temperature is high enough for it to start running faster.
You can simply get rid of it by decreasing the threshold in your BIOS. In my case, it was set to 800 rpm when the stock cooler was there. I decreased it to 600 rpm and the message went away.
If the error is not related to low speed, then I don't know. You should also tell the model number of your motherboard.