SATA Controller Issues on Precision M4500

Ever since I've had my M4500 which is nearly 3 years now it has had an issue where it intermittently fails to boot when the on-board SATA controller is set to AHCI mode. Maybe once in every 10 boots it used to fail. I set it to RAID mode some time ago which activates the Intel Rapid Storage Drivers and that seems to boot reliably.

Recently I had reason to set it back to AHCI mode and the problem seems to have got a lot more frequent, nearly 50% of the time it would fail to reach Windows. It just hangs after the BIOS with a flashing cursor.

Has anyone had such an issue? It's on the A12 BIOS and I believe it has the latest SATA drivers from Dell.

On a related note, the laptop has been used with an Intel 320 series SSD for most of its life. After the third failure I recently switched to a Samsung SSD, but I'm also wondering if it could be the SATA controller causing the failures, and if anyone else has observed similar issues? Are there any issues running SSDs in RAID mode? Could someone also confirm the max SATA speed supported on this system and if it's affected by the different modes (1.5Gbps, 3.0Gbps, etc.)

 

have you tried running the Dell Diagnostics ?