I bought a WDC Green 3TB and plugged it in. Ran HD Tune on it and got 150.8 mb/s max 95.8 mb/s min transfer rate, the other readings I don't remember. Then I realized I had plugged it in an s-ata port that according to my board's manual is 3 gb/s. So I re-plugged it in a 6 gb/s port. I ran HD Tune again and got nearly the exact same result which I thought was weird. These are the additional readings after replug: Average 122.0 mb/s, 229.5 mb/s burst rate. Are those speeds what I should expect from this drive or are there any issues with it I might want to look at?
On a Green drive, you'll be lucky to get a consistent 60-70 mb/s on file transfers and the like ( depends on how full the drive is, how big the file being transferred is, etc.). They are not speed-demons. The speed of the SATA port into which you plug your drive should be irrelevant. At speeds like these you're not even close to testing the limits of a SATA connection.
So, yeah, you're seeing the best you can expect from a WD Green drive (I know, I have 2 X 1 tb, 2 X 2 tb, 2 X 3 tb, and 2 X 4 tb green drives)