Windows 7 - Can I connect a SATA drive to an ESATA port?

I bought a cable with ESATA on one end and SATA on the other end. What am I supposed to do with it? I connected a standard SATA drive to one end and the other end to the ESATA port on the back of the computer, and used an external power supply for the drive. The BIOS does not see the drive. Suspecting the drive needed to be powered from the same power supply as the computer, I plugged the drive into a normal power connector in the computer, but used the new cable to connect it to the external ESATA port. Still the BIOS sees nothing. The drive works perfectly as a SATA drive in the normal SATA connection.

I'm not really sure what you have done. What type external power supply did you use? Is it a new drive or a used one? When your computer is on, can you feel the drive spin up? Connect the drive and start the computer. Right click on computer in the start menu, select manage. Maximize the screen and in the left column select disk management. Look for your drive there. If it is a new drive it will have to be initialized, a partition created and formatted and a drive letter assigned. If there is data on it, right click the drive and select 'change drive letter or path' in the next screen select new, from the drop down list, choose any drive letter you want that has not already been used. If it wants to format the drive don't do it if there is data on the drive you want to save. Formatting will remove any data on the drive. Let us know more particulars and we may be able to help. You can also go to device manager,
and expand disk drives and see if it is listed there. If you need more help please post a screenshot of the entire disk management page. You can use the snipping tool or paint, then upload the file using the paperclip icon in the response box.

Make that eSATA is enabled in BIOs.

Normal internal SATA drive connected to ESATA port on back of computer using a cable with ESATA on one end and SATA on the other.

One from an external hard disk case. But anyway I also tried using a power connector from inside the computer, so that's ruled out.

Used, but I tried several.

Yes. But it spins up with only the powersupply connected.

It's not listed in disk management.

It's not listed in device manager.

The drive works perfectly if I connect through the normal internal SATA port.

Yes, it was already on.

Is the eSATA connector on the computer, part of the motherboard or connected by another cable to the motherboard?

Have you tried another eSATA cable?

It's a connector on the rear of the motherboard. The supplier is sending me a new cable, although the cable looks fine to me. I was thinking I wasn't using it correctly - so it's ok to connect ESATA straight to SATA?

Yes, that is the way to connect it.
The cable should be SATA to eSATA.
Have you tried setting eSATA to AHCI in the BIOS?

Thanks. Is it true that the drive must support ESATA?

eSATA is already on AHCI in the BIOS, as are the internal SATA ports, which work fine. I'm having this problem with all computers I try (4 of them!) The vendor sent me a replacement cable and that doesn't work either! There must be something I'm missing here..... the computer just doesn't see the drive at all! And I've tried several hard disks.