Samsung LN40A550 VGA "Mode Not Supported"

Not sure where else to go with this problem. It's pretty unique and I've had a tough time getting any decent search results online. Just one thread that was abandoned years ago. Anyway....

I'm looking for someone who knows more than I do about HDTV and VGA input. I purchased a Samsung LN40A550P3FXZA in 2008. Recently, I've moved into a new house and this display is my new 'gaming' room display. I have a VGA box for the SEGA Dreamcast that worked great on the previous Vizio display, but I cannot seem to get it to work on the Samsung. It states "Mode Not Supported" when I attempt the power it on, plugged into the VGA port on the TV. I realize it's probably a resolution or refresh issue, but can anyone confirm that these two pieces of equipment are not compatible?

My tv manual states that the display supports a VESA 640x480, 31.469 kHz Hor Freq, 59.940 Hz Vert, 25.175 MHz Pixel Clock, -/- Sync Polarity. This is one of many supported modes, but I think the Dreamcast outputs here. It should output at 640x480p60 (Progressive Scan, EDTV standard) at 31 kHz in RGBHV, via Wikipedia

Also, I don't get the option to Auto Adjust when on the PC input.

With "Mode Not Supported" up, I can press Tools on the remote and get options for Device List, Picture Mode, Sound Mode, Sleep Timer, and PIP. No Auto Adjust.

From Menu>Picture>Auto Adjustment, the option is greyed out and inaccessible. It seems as though I should have the option, but it simply won't let me select it.

If I can provide any more information, Ill be happy to do so. Thanks.

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Sorry but such is hit and miss.

The only advice I can offer is to change the NAME of that input to PC or PC DVI or the others to see if it can un-gray those options.

I'm finding HDTVs are getting MORE PICKY about video modes. If you need a more capable display, you find you don't want a HDTV.

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And the wiki on it

It appears some are using some VGA o HDMI which could sidestep the rate issues. Given the part's age, those crystals and such can drift so nothing is a sure thing on old gear. Not saying that this is the issue but HDTVs are regressing in VGA capability. I can only guess you will remember when "Multi-Sync" VGA monitors came out.

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