Thanks again Jim
Fantastic support and much needed wisdom.
In an ideal world I'd replace both CPU and GPU, but I don't think I can swing that at the moment. A GPU upgrade would probably be the easiest to push through, but I'll monitor system resources etc over the coming week as per RoninEdits' suggestion, just to confirm suspicions first.
Both yourself and Bill have also pointed to the shortcomings of my existing RAID so I'll definitely see what I can do about that. If nothing else, I may be able to swap out the "Green" drives for some drives that perform a little better, though an SSD array might be pushing my luck!
Will report back.
Cheers
Andy