i can not underclock the core by -400 the maximum is -200 are you using a modified bios or something?
Nope, stock card and MSI Afterburner 4.3.0 beta 4.
I also could only underclock my core by -200. Just upgraded from the standard release 4.2.0 to the 4.3.0 beta 4 and now I can underclock the core -400. Thanks for the heads up!