How can I make a new thread?

Your threads were merged because they were all about the same issue, finding a PSU for your system.
Creating multiple threads for the same issue is a form of spam and that is not allowed here. If you have further questions about finding a PSU for your system post it in the thread you already have, don't create a new one. If you have a question not pertaining to finding a PSU for your system then you create a new thread for that question.