Dude, try one more thing. Scrap powerstrip, and load soft15khz. JUST 15/25/31KHZ. Do not load usermodes or worry about them. Set desktop at 640x840. Reboot. Call up your graphics card contol panel, and find something like 'screen resolution' and go through the lower ones. Your desktop will remain, but the resolution will change. It'll probly ask you if you wanna keep it. If you can see that, click 'yes'. (I suggest this method first, because if it goes out of sync or beyond the monitor's scan capability, within fifteen seconds it'll switch back to what it was.)
If you can't figure that out, try this: get
this, click on it. Notice it loads in the task bar tray, lower-right. Click on that, and select different resolutions same as above.
Now, if you indeed can't get the image to fill the screen with only the OSD, obviously something's wrong.