I have read a review on a motherboard which states if i use two graphic cards the "16" drops to "4" - i presume thats to do with the speed. Do all mother boards act like that? Can i use a "SLI" MB with two separate cards -not connected - for four screens or does an SLI MB have to use the two cards for only one screen? Years ago i used a graphic card with an "accelerator" connected to it - i presume "SLI" works in much the same way. But these days why not just have a better card?