Asus P8Z77 does not support esata?

Is the SATA controller in AHCI mode? Did you install the Intel Matrix Storage software? Does the drive work on other systems?

Thanks for the quick reply.
The bios is set to AHCI mode. The external drive has dual usb/esata ports. The drive is recognized as a usb drive and works fine. I'm not sure about the Intel Matrix Storage software but I believe I installed everything from the MB install disk. How/where do I check to see if it is installed?

You know that Intel Matrix Storage software is installed because it's available from the Start menu. I use it and it automatically detects external eSATA hard disks.

Before connecting your external drive via eSATA, do you disconnect the USB cable from the drive enclosure?

Yes, the usb is disconnected before the esata cable is connected. This is done with both the PC and hard drive off.

The software I have installed is called Intel Rapid Storage Technology. I went to the Intel site and downloaded the Matrix software. It failed with message that my system didn't meet the minimum requirements. My cpu is an i7-3770k.

Intel Rapid Storage Technology is fine as it allows for hot swap when the controller is in AHCI mode, but it may not be enabled on that motherboard. Is the eSATA drive detected when connected before powering up the system?

I found the problem. The sata cable appeared to be fully seated but wasn't. I unplugged and reinserted it and booted. Now it works. Must have been loosened in shipping just enough. A basic trouble shooting step that I overlooked. Thanks for your efforts to help. It is appreciated.

Best answer selected by recremar.