FM2A75M-HD+ 6 beeps error code

since yesterday my system does not display anything. When I start my host I get 3 beeps short break and another 3 beeps. Fan works but nothing else. Can anybody help me? I replaced power supply and removed two 8GB memoy from slot A1 and B1 and replaced it by a 1GB memory module. Checked in both slots. no success. I also tried to reset CMOS. I get only these 6 beeps. Can someone help me. Is it CPU, mem, motherboard, power supply harddisk?

Best cheap-pc 

What are your system specs as well please. Are you using the APU or discrete graphics etc. 

6 beeps could be keyboard/mouse related but if it is 3 beeps then a pause and another 3 then it could be something else. Try disconnecting the mouse and keyboard from the system and power on then try them in different ports. If you are using a discrete GPU you can also try removing it and connecting your monitor to the onboard display output, if this works then reinstall the GPU and try again.

This, it is an easy thing to overlook. There should be an additional 4 or 8 pin power connector attached to the board as well as the 24 pin connector. Thanks for mentioning it Piddeman, it is something I often take for granted as being connected. It is easy to forget that not everyone that posts here will know about it.