If the TV is only being detected as a Default or Plug and Play monitor, I'd suspect the cable. Look at the connector on the cable, are there any pins missing (there should be 15)? A lot of cables seem to omit the pins necessary for the monitor to communicate its supported modes to the computer, probably as a cost saving measure.
There's some discussion from somebody that started cutting open cables in this thread:
http://forums.cnet.com/5208-13973_102-0.html?forumID=146&threadID=319407&start=0&tag=forum-w;forums06
Hello,
I currently have an LN40A550 TV and a Dell laptop computer. I have plugged my laptop using the VGA serial cord into the PC input of my TV. I get a display, nowever the aspect ratios are not correct. When I go into my display settings it is only allowing me two aspect ratios to chose from (800 x 600 or 1024 x 76
. My computer only recognizes the TV as a "default monitor" ...it makes no mention that it is a samsung 550. Is there anyway I can get different aspect ratios so the display doesn't look stretch and I can get a display with 1080p?
Thank you for your time.

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