Can't change refresh rate...

I am using fullscreen exclusive mode and would like to be able to change the user’s refresh rate to 60hz in hopes of vsyncing the game at that rate. I am creating a DisplayMode object with:
width: 320
height:240
bit depth: 16
refresh rate: 60

You would think that this would change my display device to use that mode without any trouble, but… when I look at the resolution and refresh rate from a menu built into my monitor, it shows 640x480 and 75hz. The 640x480 part must be incorrect because the game is contained whithin 320x240 and this uses the fullscreen, and if I set the mode to 640x480 it only takes a corner (monitor still shows 640x480 when I do this). The part about it showing incorrect resolution is not important, the refresh rate it shows is true however. I know this because my program is not vsync limited to 60fps, but rather 75 which is the refreshrate my monitor shows despite the fact that I set it to 60. My display device must support that mode because I compare the mode I am attempting to set it to, to the available modes and it goes through, not only that but it seems like an exception would be thrown or something if my display device didn’t support the mode and it was somehow getting past my check for compatibility. Anyone know whats going on?

The 640x480 part must be incorrect

Actually… it’s not.

I know it’s somewhat weird but if you use 320x240 it’s infact 640x480 with 2x2 pixels (the graphic card does that on it’s own). [I’m not sure if all cards do that]

And 512x384 becomes 1024x768.

However, everything >= 640x480 uses usual 1x1 pixels.

ah, that explains that part…