brad is mostly correct. having ssd and hdd with BIOS set up as RAID does not mean RAID is all set up to go.  here is Dell info: Can your system support a RAID Configuration? You must have two Hard Drives of equal size and capacity installed. This type of RAID does not involve a hardware RAID card and instead uses the BIOS along with the Intel Chipset and matrix storage software on older computers or with the Intel Rapid Storage Technology on newer models to create a type of Software-controlled RAID. This type of RAID configuration will only support RAID 0 and RAID 1. How to configure RAID on your SystemYou must have two Hard Drives of equal size and capacity. You must have decided if you want to use RAID 0 or RAID 1. Dell recommends RAID 1.RAID 1Mirrored Disk Array - Provides redundancy in case one of the two drives fails. This allows for all data to be duplicated, but is not as fast as a RAID 0. If a disk fails, the data can be recovered from the second disk. The drawback is you half the size of your total capacity, and it is slower to write and it does it to both drives. The benefit is if one disk fails you still have all your data and can rebuild from the surviving disk. Typically, in a high performance desktop, you want to design storage like this:Two disks or disk groups:1st Disk group: fast, low capacity volatile group.2nd Disk group:  slow, high capacity, highly redundant group.install windows, programs and games on the first group, then store music, movies, pictures, game saves and other on the second group.For the first fast group, aim for a single SSD that maxes out controller's speed For the second disk group, aim for a couple of 2TB 7,200rpm drives in a RAID1.
I do wonder because I don't wanna lose files, games or etc, so could I really use one for storage and the other for performance?
Can I use a HDD for storage and an SSD for performance?