SD just displays as 2x (which is still smaller than hd). My next step would be to find out if its the hdlink box or the monitor. Or maybe the hdlink doesnt like the monitor (refresh rate?). Take the hd link back and get a new one it might just be broken or have a bad firmware load, because it should just work.
ps.. i dont ever remember setting the monitor up on the mac before install of hd link, the hdlink is literally the video card (HDSDI to DVI).. Can your monitor handle what the hd link is asking it to do. 1920×1080 48i (23.98psf), 50i etc. check the Monitor specs..
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