I see it says CPU usage = 100%. I think you might be hitting a processor bottleneck. This is not normal for even 4x drive RAID-0 regular drives, so there's definitely some kind of issue here. I'm sure there's a reason, but frankly I'm just too tired to think it out right now.

I do notice though that your 128k stripe size results seem to show the highest read/write results, much more than the 16k stripe sizes. Perhaps the low access times, coupled with the increased frequency in going from stripe to stripe has something to do with it. As far as the burst rates go, yeah... I pretty well just ignore burst rates for many reasons.

This is one of the issues with onboard & SSD's - they really just don't generally play well. Perhaps ICH10R is better, but I suppose we're going to have to wait a bit for conclusive results.