New CPU, Mobo and RAM, do I need to back files up on HDD?

Unfortunately you will need to reinstall. Your HDDs currently have the old mobo drivers and the info is stored in the Windows registry. It is because of this that you will likely encounter endless BSODs by simply doing a plug and play with the new mobo.

It's always best to do back ups when you change any hardware. You might get it to work (I didn't have to do a reinstall after I changed my mobo some years back on winXP) but as T_T said, the drivers from the old mobo can cause you lots of problems.

T_T is correct just to give more than one opinion , its back up time

RAID 0 'transfer' has nothing to do with the 'drivers' -- it has everything to do with How the RAID is setup AND the Controllers on the MOBO OR Controllers on a RAID Card.

Moving a RAID is Hit and Miss and by far more Miss. I noted your MOBO uses nVidia so I can 99.99% guarantee the RAID won't transfer to a new MOBO using (Intel, Marvell, AMD, etc) Controllers.

I treat RAID 0 as if it's going to go 'poof' at anytime, it's too volatile -- one loss drive and all your data on it is gone for good. It's fine for an OS, Apps, and working data.

That said, it would be CrAzY not to back-up your data -- now and always. IF it were 'my rig' I would transfer the data, full format and setup the RAID on the new PC from scratch.

Further, IF the HDD's are >3 years old then it's probably time to retire them and get new HDD's. However, rare for me to say, keep them for ~6 months more. *Problem - Thailand manufactures most of the World's HDD's and the massive flooding has caused the prices to skyrocket 270%+ the shortage will last for up to 6 months.*