I was having some issues with my SSD on my M4A785TM-M Evo motherboard, ended up buying a Highpoint 620 controller, so I could use MSACHI (ie TRIM) Even so TRIM wont effect read speed. Are you using a SATA 2 cable (300MB/s cable) not a SATA 1 (150MB/s cable). Have you tried a different SATA port. Some motherboard share SATA port bandwidth with different devices. Also what are you using to test. I would recommend HD Tach (would need to run in compability mode), HD Tune, ASSD, or Crystal Disk Mark.