I just bought a 120gb sata3 extreme and i am seeing slow speeds using crystal disk only gettin 272 read and 151 write which is slower than my wd velociraptors were in raid 0 i have set the bios to AHCI is there any thing i am missing and yes my motherboard is sata 3 (6Gb per sec) my mother board is a MSI 870A-G54 my CPU is amd 975 black denb running 16gb gskill ripjaw ram and i did a clean install no migration i checked reviews on new egg where i bought it from and people are seeing speeds up around 450 read im not sure where im going wrong with settings if that is the cause thanks 
also running windows 7 64bit home premium i have all the latest drivers for everything short of reflashing bios
What transfer size ore you seeing tat speed in? Best way to benchmark it to see if it is working correctly is using ATTO benchmark. It is a free download. Just run it in its default settings and you should see the full speed.
Looks like SATA II speeds to me, should be much better than that. What AHCI driver are you using, AMDs or Windows, or what?
The sequential read and write speed numbers you quoted are only one aspect of a drives performance, and when used as an OS drive, all the other types of file speed access, such as 4K and 4K high queue depth are much more important, and I’m sure far better than and HDD in any RAID array.
