Using "dual channel" option - is wrong, because you will see noise, and your eyes will suffer by seeing the picture on the monitor.
Put the memory either in A1, or in A1 and A2 slots if you have 2 modules. Never use "dual channel" configuration. Leave all other slots empty. Use only slots, that meant for "single channel" configuration. By using "single channel" memory configuration, the picture won't be broken, it will be correct.