2013 27" iMac using mini displayport to VGA, external monitor off center.

I recently purchased a new 2013 iMac 3.5 i7 and connected two external monitors. The minidisplayport to DVI adaptor works fine on one monitor but the minidisplayport to VGA is off center on the 2nd monitor. There is a 2" black band on the left side of the screen. I've replaced the adaptor, cable and tried on two different monitors. I've also tried repositioning image in the monitor settings which it can't move far enough. It only happens on 1920 x 1024. Any other resolution is fine. Other than that it works fine, but this space is going to drive me nuts. Because these are 23" monitors I really would like the highest resolution possible. I'm stuck. Any thoughts?