In reply to a post by gouledw:

No, but what you could do depending on who your ISP is, get the business hub, plug it in and ask them to set your Noise Margin to 6dB. The business hub will hold down to 1dB from what I've seen.

It will sync normally at 6dB but once it is happy te line is stable it may drop to 3dB

And below ... I have once seen mine with a negative SNR! A couple of images showing very low 0.5dB SNR

http://i2.photobucket.com/albums/y31/Polchraine/TBB/...
http://i2.photobucket.com/albums/y31/Polchraine/TBB/...