Lower noise margin than normal.

Im capped at 8mb and know that for absolutely ages my line is capable of holding this speed at all times of the day but recently i've noticed the noise margin dropping in the evening and i'm having to reset my router and then get slower speeds ie 6-7mb, been on to sky and they are telling me there is nothing wrong with my connection and thats what my line is capable of.
Now this has all tied in with a faulty power supply, i replaced the psu while on the phone to sky and still no change to my connection, but they still can't see that a week or so ago i wasn't having these issues and now i am any ideas?

Have you restarted the ADSL modem since replacing this PSU...or was it the ADSL modems one?

All many of things act to increase the level of noise in the evenings, without seeing your full stats both in day and at night hard to say much else, other than xDSL has no guarantees that it will hold the same speed now that it did a year ago.

In fact as more people get xDSL in an area overall speeds decrease due to noise from all the other lines, not massively usually just 300-400Kbps.

yes it was the router psu. spoken to sky again tonight and they've restarted dlm and the noise margin has increased so looking better already, cheers for your reply, i'll post the final outcome in a few days