Is this your GPU? If so it looks as though it needs two 6 pin connections. Also what make and wattage of power supply are you using. The power supply is a very important part of modern PC's and you should never buy a cheapo if you can help it.

Oh dear, why on earth would you think that they would go to the bother of putting two connections on the graphics card if you only need one. But all is not lost, you will need to get yourself one of these and Maplin's do them PCI-E converter.

Your 430W PSU is just a little more than the minimum needed by your graphics card which is 400W but you really should have a 500W as a minimum as you have very little spare capacity.

When planning a build I spend weeks researching components, making sure that they will all work together but I must admit when I first started I did not and had many problems along the way. But I learnt and now check compatibility,power needs of the components, has the PSU got the connectors I need ETC ETC. So don't worry that things have not gone as smoothly as you would like you'll get there.

Scroll down to IBM Beep Codes and you will see that it is a video problem, in your case probably not getting enough power.

Codes.