In the main search tool at the top of the page, type in the topic you are wanting to look for. The forum doesn't have a built in search function for within the forum sections. Everything is handled through the main search.
You just use the search bar are the top of the page, and then use the filter options to narrow down the results. It's not a great tool, but it's all we have for the time being.
Search for - Crossfire on Asus P5KC with 2 x ATi Radeon HD 5450's? Then give me an answer please