First, you have mismatched RAM. Take the RAM settings off AUTO and set them to 266 MHz (CPU FSB freq) / 533 MHz RAM clock / 1:1 CPU:RAM ratio. Raise the RAM voltage to 2.2 volts. Then you shouldn't need to remove the slower RAM.
Then take a look at one of my old threads:http://www.tomshardware.com/forum/268247-29-overclocking-e8400