Here’s something that may interest you “techies” out there.
Sorry about the lengthy preamble but it’s necessary.
I’m using an Asrock 960GM/U3S3 FX motherboard, which has 2 x Sata 3 connectors and 4 x Sata 2, it also supports DDR3 memory (1866 OC) and up to an 8 core CPU, I’m running a 6 core AMD FX 6100. The board uses the AMD 780G chipset for the Northbridge and the SB700 for the Southbridge.
To take advantage of Sata3 I recently purchased a 128GB SSD from Sandisk. Before making my purchase I checked the Sandisk website where I found the key information I needed about the products performance. According to Sandisk this device will give, and I quote, “Write speeds of up to 350 MB/s and Read speeds of up to 490MB/s” They even disclosed the software used to obtain these figures; namely ATTO Disk Benchmark and the parameters they used. These were a Transfer Size of 0.5 KB to 8192, a Total Length of 512MB and a Queue Depth of 10
I duly fitted my nice new SSD and after making sure everything was as it should be i.e. AHCI and TRIM were all working, I downloaded ATTO from the web. I ran ATTO using the same parameters used by Sandisk but the results were quite disappointing; Write speed of 260MB/s and Read speed of 370MB/s. At 128k the Read speed hit 370MB/s and there it stayed throughout the remainder of the test, likewise, the Write speed hit 260MB/s. It appeared as though the SSD had reached some sort of maximum but, I couldn’t understand what, I knew it was capable of performing better. I did some tuning in the BIOS, there is a whole section devoted to Overclocking but, I couldn’t improve the Write/Read speeds.
I decided a new approach was needed so, I took my SSD to a pal whose computer has a Gigabyte motherboard (sorry, I don’t know which model). The ATTO test reported very similar results to those on my Asrock board; however, the difference with the motherboards is that the Gigabyte drives its Sata3 ports from the same bus clock as the PCIe. By default this clock runs at 100Mhz, however, its configurable. We increased the speed to 110Mhz and ATTO reported a Write speed of 290MB/s and a Read speed of 410Mb/s. We increased it again 115Mhz and the disk figures were even more impressive.
OK, I thought I’ll go home and do the same on my Asrock . However, once home I discovered that my Sata ports are controlled by the Southbridge chip (SB700) and that the bus speed is fixed at 100MHz.
So, my question to you techies is “why make a chip that supports Sata3 with an advertised throughput of up to 6Gbits/s and then throttle them by limiting the bus speed to a 100MHz?”