Output powerIncreasing your output power will increase your signal strength.. which in turn may increase your SNR.. which may increase your sync speed.
Woooooooah great I hear you say - increase the gain on my line and get a better sync
However signal strength can also be adjusted as part of the
bit swapping process... and also many bins (particularly in the lower frequences) may be masked to ensure that power doesnt go above xdB... and also there will be some settings on the dslam to ensure the power level cant be increased above a certain limit. (Other wise your line could drown out neighbouring lines causing crosstalk at the dslam. Short lines will also often find that their output power has been reduced to prevent this.
A certain amount of leaway/overhead is also needed on some lines in order to give spare incase the bit-swapping process needs it. If theres not sufficient overhead, and your SNR does decrease, then bitswap may not be able to work in the way it was designed and you could loose sync at an earlier stage than you would do normally. Theres a reason why some leeway is needed and therefore its not unusual to see a line sync up with say 18dB power, but increase to just shy of 20dB during peak.
For all of the above reasons, tweaking the output power may not work/and/or is not recommended on many lines.
