In my computer i have 3gb of ram, it showed up a 3gb untill i did a bios update (v1.5 to v2.30) and now it shows up as 2.9gb
should i be concerned about this?

my motherboard: 939dual SATA2

Your bios probably has integrated graohics so it staels some of the RAM.

If youve got a PCI-Express graphics card, you may want do disable the integrated video in the BIOS menu.

I would not worry about. Total memory readings can be miss leading. Depends on the apps and os what they are doing with it. If you have 3gb and are only seeing big deal.