I replaced the memory sticks, and while doing so I disconnected the CPU's fan because it blocked the forth stick. At first the computer didn't turn on and started to make many beeps, so I tried again and after making sure the sticks are connected properly I turned on the computer and now it's working as it should. Yet, I am not sure the CPU's fan is connected properly, and that the case fans work properly as well. The computer is more than 3.5 years old, it includes i5-2500K (without an overclock), its fan is Scythe Yasya, motherboard P67A-UD3-B3, memory 4X8GB, case Lancool K60W, power supply Corsair TX 750W, video card HD6950 2GB and two hard drives SAMSUNG 1TB Spinpoint F3 HD103SJ, Seagate Barracuda ST3000DM001 3TB. After turning on the computer, I got the following results with SpeedFun and AIDA64: I am not sure about the results, because it shows that 3 fans (two of the case and the CPU's fan) are 0 RPM according to SpeedFan, and don't appear at all in AIDA64. Are these results normal? How do I check if the Case fans and the CPU's fan are working properly, and if they don't work properly - How do I fix this?