Latitude d400 CPU question

This is a bit bizzare, but i swear it is true.

I bought a used Latitude d400 off ebay. It has a 1.6ghz pentium m.

Everything from the bios to both operating systems (xp and fedora 14) claim it runs on a pentium m donthan.

I thought d400= banias. it does have ddr 1 RAM, the firewire port, and the 855GM extreme 2 graphics. it also had the non-hard drive warranty void sticker still untouched.

was this a late run of d400's with the upgraded cpu (and 2mb cache) or is something screwball going on?