I recently bought two new sata3 drives and set them up in a raid stripe and installed win7, all work fine.
I added an older sata2 drive, it shows in the bios but Windows 7 cant see the drive.. not in disc management or device manager...
I had a similar problem with my other sata2 drive but that one showed up in device manager as a 'scsi' and after a few reboots suddenly showed up in disc man. but after disconnecting that to try the other drive its now got the same problem.
My first thought is the always-popular "partition and format," but it sounds like you have used these drives before.
My second thought is: what motherboard and what SATA connectors? Some motherboards have SATA ports through the chipset and also through an additional chip. Ports on the additional chip may require enabling / configuration in the BIOS, and will require that drivers be loaded.
My third thought is that one or both of these drives is failing, or that your cables are loose. This is based on the drive that winks in and out as you describe in the second paragraph.
So I can't narrow it down for you. See if any of the above help.
Both the drives are already formatted and have data on them.
I was using the cable from my sata blu ray drive which still works when i plug it back in but shows up a scsi..
the first drive connected came up in device manager as scsi which i thought was a bit odd. it then showed up in disk man after a few reboots and i was able to 'import foreign disk' and it worked ok for a few days untill i swapped it to the other spare drive and now neither shows up in device man. or disk man.
I only have 4 sata ports on the motherboard and have tried different cables in the 2 remaining slots with the same results (both of which work with my sata blu ray drive)
As for jumper settings they are sata drives so have no jumpers for master/slave, if thats what you are refering to area51reopened.