We're first time computer builders. Doing a build outside the case in the event there would be problems and there are. We got the intel i5 chip in the motherboard, connected the graphics card, monitor, two sticks of memory in the two slots, power supply and connected the power switch wire from the case to turn it all on. The power supply and cpu fans turn on for a second and then shut off, then turn back on by themselves again and shut off. They do this over and over until we shut off the power supply. The power supply is good. We paper clipped the dark green wire to a black wire and connected a case fan and they both stayed on. Any ideas? Do you need more information? Thanks!
Make sure the cpu heatsink fan is in the correct cpu fan port on the board. Turn the board over and be sure the white center push pins for the heatsink are all evenly sticking out when seated. Reseat the power supply leads to the board and the ram. The ram should make a firm click noise on each clip as you press it into the slots.