CRC Error's and SNR

[PiKe]

I've had DSL for 3 years or so, for as long as I remember I've always had CRC error's but on services 2mbit and below they didn't effect the speed of my service or cause disconnects. However on Max they're causing me headaches, the SNR margin is above the 6dB limit BT set for Max services all the time however, CRC error's appear to roll in which I cannot understand.

Why is the data getting corrupted if there is sufficiant signal to noise ratio?

I can sync at 8mbit and there's margin to spare so I know the line would be able to take it if it wasn't for the CRC Error's. I sometimes receive several hundred in just a few seconds causing the router to drop the connection and resync with the exchange (sometimes at a higher(?) speed). My lines current sat at 5mbit with 15dB SNR and this moment in time I'm getting 2 CRC Errors per minute.

What's causing the CRC Error's and if it's noise, why isnt it being reflected in the SNR?

 

[PiKe]

I've seen people with very marginal stats getting little to no CRC errors on their line, yet me, with plenty of signal, manages to clock up thousands an hour.

I've already explored the possibility of the phoneline fault, a battery fault was found but fixing it did precisely jack.

Ring wire trick isnt possible because I have no slave sockets, so theres no ring wire to disconnect in the first place.

Thanks for your reply though.

 

[PiKe]

Well i know about CRC errors comes down to a noisy set of wires and that many modems give out the not so accurate of readings, but good luck dude

Tried 3 routers, 2 DrayTek and 1 Billion, so I can't see it being that.