Please check your mainboard’s BOM version. If you don’t know how to identify, please visit our website at following page.
http://www.shuttle.com/share/fae/hq/faq/mainboard/qa/Mainboard%20MB48N%20V1_3.pdf
This mainboard supports DDR333 since BOM 12. Older BOM version does not support at all.
Links concerning this chapter: