See this Article from an SC440 owner in Japan:

http://usy.jp/pc/poweredge_sc440_8gb/

Use page translate.

He was using PC2-5300 ECC Unbuffered RAM.  I will try PC2-6400 ECC Unbuffered 800Mhz RAM. Hopefully, it is backwards compatible to 667Mhz and 533Mhz.

I already installed 8GB PC2-5300 ECC unbuffered RAM and it works just fine in the Dell PowerEdge SC440.

http://webcache.googleusercontent.com/search?q=cache:IJMyPClKJe0J:en.community.dell.com/support-forums/servers/f/956/t/18946794+&cd=1&hl=en&ct=clnk&gl=us