I have just built a new sys based on the Asus A8Nsli. I am having a prob. When I have just 512 (2x256) everything boot fine etc. When I put the other 512 (2x256) the sys seems to be booting but the monitor does not receive signal. Thought it might have been the older ram. Ordered a new set of DC ram identical to the other ram that is working in the A slots. Same situation. Is there a jumper or something else that needs to be changed?