The grey out only means bootable condition. Moving on.
If the drive was formatted the Windows installer is known to do what you wrote so I like to boot up a GPARTED CD (widely written about on the web) and remove all partitions from the HDD.
Next time you post, tell details like the HDD make and model. There are old PCs that don't support 1TB and up HDDs.
This is a very old computer I took out of storage to try to get it up and running with a new drive. Any Sata drive I install shows up but is always greyed out in the bios. The Sata DVD drive is also greyed out but it does work. When I try to install windows by booting from the DVD drive it attempts too but then tells me there is no drive to install too. I've gone into Integrated Peripherals and its set to SATA 1+2 . If anyone has any advice I'd appreciate it!