Maybe. According to the spec sheet the mobo only supports 533 or 800 FSB speeds. But the manual claims it also supports 400, but only for Northwood processors.
You might need to buy a new processor for this mobo, I don't know if yours is Northwood. Plus, since 400 support is so limited, and so "old news", I doubt they tested 400 very much. So there'd be some risk there.
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