Ah, OK. I didn't see your posts as a SATA II vs. SATA III, but rather as asking about the "best slot to use".
It also seemed mentioning the limitations with these low cost SATA III controllers (due to PCIe 2.0 specification @ 1x lane = less than what SATA III can actually sustain).
As per boards not running at full speed, there's a couple of possibilities;
- Low cost 3rd party SATA III controllers (same ASM1061 or similar, such as that offered by Marvell).
- Pipeline the chipset connects to the CPU was limited in order to allow for all controllers to be able to push data (things like Ethernet, USB, and audio won't stall due to SATA devices hogging all of the available DMI bandwidth). Intel has done this with former ICH parts (i.e. SATA II limited to ~ 660MB/s for the SATA II controller, and it appears they've continued with this with DMI 2.0 as well - it keeps it simple = lowers costs).
The controller used can only operate two ports. To keep costs low and give the user flexibility, they used jumpers to allow the user to select the port types/combination they want (all internal, all external, or hybrid <1 int + 1 ext>). Other companies, such as Highpoint, don't offer this capability (Highpoint offers a 2x internal port and 2x external port cards), and newertech only offers an external version.
It's a good compromise IMO, as they're still inexpensive and users do get the added flexibility.
