is forum signature can help your serp ? how if the forum topic not relevant with our site ? help me solve the problem ?
Signature links adds value to fast crawling and a huge number of backlinks to site adds a huge value. Relevance always matters. its completely depends on the competition what you need quantity or quality.
I use sig links to get my latest blog posts indexed, I add it to my sig for a couple of days and hey presto they make there way into google. I've not seen sigs significantly impact rankings for a while though..
You can get one way links with forum signature and its one of the ways that helps your site get index.