just brew it! wrote:
Did a little more digging.
The Marvell 9128 chip used to provide the 6Gbps ports on that motherboard is a notoriously poor performer. Firstly, it interfaces to the northbridge via a single-lane PCIe 2.0 connection so it's hobbled from the get-go. Secondly, it's just plain s-l-o-w (and doesn't even come close to saturating that single PCIe lane).
OK, this is it. Thanks for the info which is much more in details than that in the article or forum post I previously mentioned. Since I got this mobo, the interface of the HDDs I used were all SATA II, so I have not been much concerned about the issue of Marvell SATAIII controller.
As counter-intuitive as it seems, you actually might get better performance by using the SATA 3Gbps ports!
I did run HD Tune with the SSD connected to SATA II and got essentially the same readings.
If you want to utilize the full potential of your SSD, it looks like you need to get a decent SATA 6Gbps controller. This is going to either mean a new motherboard, or a decent PCIe x4 controller installed in your second PCIe x16 slot (assuming you're not using dual video cards).
Aside from this problem, I was beginning to think that I had used the motherboard long enough, so getting a new one is not bad idea at all. On the other hand fixing the problem by a PCIe x4 card you suggested is something I am also interested to try. I will research both options to determine the cost consequences.