Windows 7: external sata (esata) problems

using Build 7100. I've got an external vantec case for a hard drive that can be used as either esata or usb. If I use it as a usb drive; it works perfectly with no issues but it relatively slow compared to esata. If I use the drive with the esata connection; it takes time to recognize the drive; it appears to read fine but the write speeds can be crazy slow or really fast. Sometimes it just hangs the system for 10 minutes or more;

I do have a Dell system running Raid on the sata internally. I was wondering if it conflicts with the external sata. Might explain why the usb connection works fine. It's the X58 chipset.

The Intel Matrix Storage Manager takes about 5 minutes to load when the drive is used with the esata connection. The manager mentions it is using Port 4. Using transfer mode: Generation 2. Status is normal.

It's very annoying to have an external sata drive that only works correctly with usb and not with esata.