I should protect myself.  I know this works for my 3150, but I don't have a drop down menu for my dpi settings like the new machines.  I have to change the dpi, which I never do, by doing a linux command.  On my 1224 HDC, I have a drop down menu but I never have to change it.  I run everything at 1200 x 480.  It doesn't make a bit a difference in speed if I run at a lower or higher resolution.  Let us know if this works on your 3150x2 since you're changing DPI alot.