@Rogd66  It depends at least partly on the RAID controller.  Some will allow you to set up a RAID virtual disk while preserving the contents of one of the disks that will be part of the new virtual disk being created.  But typically setting up a new RAID virtual disk comes with a warning that the data on all member disks will be erased -- although you'd get a warning about that beforehand.  You could try just going into the Intel Rapid Storage management boot-time interface and seeing what happens.  But the additional potential complicating factor is that if your system is currently set to AHCI mode rather than RAID mode, you'll have to change it to RAID mode before you can even do that, and switching between AHCI and RAID mode causes a Windows installation set up while the system was in the previous mode to become unbootable.  I've read that if you want to switch an existing Windows installation over, you can make the change, boot once into Safe Mode to allow Windows to reconfigure itself, and then boot normally from then on, but I haven't done that myself.

But since you're considering RAID 0, have you checked benchmarks of RAID 0 setups on that system?  The reason I ask is that depending on the system design, RAID 0 might not give you much of a performance boost anyway. It depends whether the system has dedicated PCIe x4 interfaces for each M.2 slot wired all the way back to the CPU, or whether each slot has a PCIe x4 interface wired to it but the two of them share a single PCIe x4 connection back to the CPU. In the latter case, then you'll only get PCIe x4 performance across both drives -- and considering that modern NVMe SSDs can saturate a PCIe x4 link singlehandedly, you won't gain much by adding another one. About the only benefit you might see is the ability to write larger amounts of data at high speed because you'll have effectively doubled the size of your write cache by having two SSDs in RAID 0, so it will take longer to fill that up before the write speeds of the SSDs drop since they'll have filled up their write cache and will then need to write directly to slower flash memory at that point.

But if you do go with RAID 0, I would strongly suggest making frequent backups, because a two-disk RAID 0 doubles your risk of data loss due to drive failure since a failure of either drive causes you to lose all data.

thanks for the info I think I'll just leave it as two separate drives

@jphughan 

That was borderline poetic

Yep. With our production file-servers we choose either Raid-1 (a set of mirrored drives) for redundancy, usually the boot drive.  Either drive can fail. No worries.
And/Or Raid-5 which is 3 drives or more.
With 3+ drives, data is spread across each drive, with the last drive acting as "Sum" drive. The algorithm being 1+1=2.  With this algorithm, any drive can fail, and is replaceable on the fly...no shut-down. When the new drive is inserted, the system can, and will, rebuild all the data on third drive automatically.
The beautiful thing about Raid-5 is it can have unlimited drives, as well as improves performance 50-80%, depending on your application, such as a large, number crunching, accounting system.
I took the National Heart Foundation's month-end report from 10 hours to 2. I didn't even give them new drives, I just Raid-5'd the ones they currently had.
Raid-0 has no purpose, perhaps a little bit of performance gain, but double your chances of full system failure if either drive fails.
So, you could go to a mirrored-set, Raid-1 easy.
Either an OS-software-based mirror easy.
Or a hardware/firmware/low-level Raid1, unfortunately, with Raid-1 you lose alot of storage space, as you now have 2 boot drives. With Raid-5, you lose 30% of your storage.