RAID question and problems

Hi there,

I've had a RAID 0 over my motherboard for 2 1/2 years without a problem (of course everything is backuped). As a video editor I need the space and speed (12 TB SSD would be way more expensive). In the beginning I got around 400 MB read / write. Now I checked again with AJA and Blackmagic disk tools. There seems to be an anomaly: It starts pretty fast but then constantly keeps dropping. When I benched with my OS and Scratch SSD that was not the case; the speeds remained +- constant over the 4 & 16 GB Benchfiles. With the RAID 0 write ends up aroun 200, read under 100 MB (sometimes as low as 60 MB!) which seems very slow even if theres data on the RAID (4 x 3 TB WD RED, non pro)

Questions:

- does this mean one of drives starts to die?
- can I check every singel drive without deleting the RAID 0?
- should I switch to software RAID?
- would a hardware controller give me increased speeds? I thought about the Adaptec 6405 with 512 MB cache and 4 ports. I don't need anything other than RAID 0

Thanks for the help.

Cheers

PS: I just overclocked my 4930k to 4.4 Ghz with offset (voltages up to 1.38), but I guess that isn't the issue.

How full is RAID?
Have you updated anything in the meantime? BIOS, motherboard drivers etc? Windows update?
If 1 drive dies you whole RAID drive will be gone, so this is not the problem.
Sounds like some drive etc. issue, not hardware.
Overclocking may be easily the issue as you quite often adjust some other controllers frequencies by overclocking CPU.
Start with going back to base clock and testing.