Resolution is typically a BIOS issue. I can't speak for other boards, but the SP13000 can do 800x480 with the proper BIOS. I had to flash mine, but they might come from the factory with the latest BIOS now.
But before you toss your current board, you really ought to see if it powers up from a desktop power supply, and if it does, flash it with the most recent BIOS. You might just be pleasantly surprised to find that not only does your mobo work after all but already supports widescreen displays.