Is that computer running Windows? In case it is (using BIOS RAID 1) 2x 3TB= 2TB, iow your HDD just became 3 times as expensive, and (using BIOS RAID 0) 2x 3TB= 4 TB, iow 33 % overhead. So depending on what you want to achieve, I would go for a software solution, like an automatic backup solution or a software "ghosting", whereby you can split each drive in two 1.5 TB volumes. The BIOS RAID won't be able to use more than 2 TB per HDD with Windows.
If you're not running Windows on bare metal, but rather in a VM or not at all, you'll have 3 TB available in RAID 1 and 6 TB in RAID 0. If you're Windows liberated, you can also set up a RAID 10 array with as little as 2 HDD's, whereas you'll need 4 of those if you use Windows as main OS, whereby as always, Windows can only use up to 2 TB per HDD.
What do you need the RAID for, performance or redundancy?
im not worried about losing what is stored on because its ONLY for games. i can Always reinstall the games since i own the copies. (as stated in my first post ^_^ )
ive read also the windows way which is kinda similiar to the BIOS from what i can see.
you guys are very helpfull and im greatly greatfull for that. thank you