To filter the noise, have few more hoops for a newbie (for example registered <2 weeks) to confirm that they thruly are creating new content. After pressing a post or reply button there would be questionaire with a search box and link to a FAQ and some additional quetions which the poster would be required to answer:
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If you have a question, it is probably already been answered:
<FAQ link to section device>
<FAQ link to section software>
<FAQ link to section xxx>
And check if there is existing thread for your issue:
Search: [________________] [Search]
Hereby I confirm, that
[ ] I have checked the FAQ
[ ] I have used the search
[ ] I'm the master of universe
[Ok, I'm a sane person - let me post]
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After the newbie would have answered, s/he would be allowed to write. This procedure could be applied on those boards which have noise or periodically. If there is resources, there can be additional moderation, greeters etc.