The benchmark is good for reading, here the link from OCZ: http://www.ocztechnology.com/res/manuals/OCZ_Agility3_Product_sheet.pdf
The reading is up to 180MB/s and writing is up 105MB/s (AS-SSD). If you use the ATTO(Crystal Disk Mark) to test then you will get read speed (550MB/s) and write (500MB/s).
Also your MB is using the AMD SATA driver that is slower then the MS AHCI driver, if you use the AMD i think you try to uninstall the AMD one (using the default microsoft drivers ), and run the benchmark again, you can check out the link (someone try it).http://rog.asus.com/forum/showthread.php?12882-AMD-AHCI-vs-MS-AHCI-SSD-Testing
And last word: Don't try to benchmark too much and it will hurt the SSD performance.