I have 2 systems in which I've tried a SATA III (SATA 600) SSD that's rated at circa 550MB/s. When I run ATTO Disk Benchmark, the maximum read speeds only reach circa 300MB/s which is the limit of SATA II (SATA 300).
Both the Motherboards support SATA 600 and yes I have verified with 3 separate Windows software that the drive is running in SATA 600 mode.
I then came across this Quote from this website:
"Before we get into testing we would like to point out a few issues that surround SATA III. SATA III was first introduced on Intel X58 chipset motherboards via a PCIe to SATA III bridge from Marvell. Two versions were introduced, one with RAID and one without. Both versions served its purpose; allowing read speeds that exceeded SATA II specifications. At the time only one product was available that actually needed SATA III, the Crucial C300. The Marvell SATA III bridge chips found on many X58 motherboards will not allow your 2011 SATA III SSD to reach peak read or write speeds. To be able to do so you need an Intel or AMD based chipset with native SATA III capability like the MSI Z68A-GD80 B3 that we are using today."
So back to my question, it now seems like the reason is because my Motherboards don't support native SATA III (SATA 600).
Is there a way around this apart from changing the Mobo? I guess using a SATA PCI-E card won't work as it wouldn't be native either?