HighPoint's Cards tend to be very weak on IOPs @ 4k. I just installed their flagship card ( RocketRAID 4520 ) into my new server, and ran a bunch of benchmarks. Under 64K there was absolutely no performance gains from adding additional drives to the Array. I was using Samsung 840 SSD drives, and tried them in raid 0 for single drive, 2 drives, 4 drives, 6 drives. Already contacted HighPoint and they said they are working on a firmware update and are aware of the issue. Even though the speed at 4K is weak, HighPoint makes very reliable cards. I have been running a 4310 in my current server with absolutely no issues to speak of for 3+ years.
If you want to see my benchmarks, I have them posted on my blog.