I recently upgraded from a Dell Latitude E6510 laptop to a Dell Precision M4600 laptop. I have two monitors connected to it through a port replicator, one through DVI and one through VGA. I'm having a problem with the VGA monitor. The old laptop would display 1920x1080@60hz no problem; the new one won't do it at all. At best, it would run 1920x1080@30hz, but I can't bump it up to 60hz. If I turn off the "Use EDID" toggle, I can force it to run at 1920x1080@60hz, but the monitor itself then won't display anything ("Input not supported"). If I connect the monitor directly to the VGA port in the back of the computer, I get the same problem. The best resolution I can comfortably run at is 1680x1050@60hz. I've tried switching the cables and using the DVI port, and that doesn't work either. If I swap back to my old laptop, the monitor works fine. I've also tried with and without a KVM, which doesn't help (not that I really thought it would), and a mac has no problems displaying the full resolution. Any ideas what could be going wrong?
OS: Windows 7 x64
Monitor: AOC e2243Fwk
Graphics card: AMD FirePro M4000 Mobility Pro Graphics