I believe I bought the wrong hard drive. The seller said the WD has 6 g/s, 32mb, 7200rpm, and 1TB for $65. I bought it without looking up for 6 g/s. At home, I opened the box and realized it's a blue WD with 3 g/s. I must have taken a wrong one, so I am not sure if the opened HD is returnable.
Here's what I am wondering: should I keep it, or return and pay $30 more for the one I wanted? Actually, I don't know the different because I am new with the modern PC building (I built back in 90's, and never did since that day). It's a 1TB drive, which means I am going to use it for a very long time. I wouldn't like to regret that in a year or more years later.
If you didn't receive what you paid for, then I would return it (at their cost) and demand you get what you paid for.
The 3.0 Gbps speed is associated with SATA II specification for hard drives, the 6.0 Gbps is SATA III, which is a newer drive speed that has been out for about 6 months or so. It still isn't prevalent for mechanical hard drives because they can not transfer data that quickly. Essentially, the speed of a SATA II hard drive and a SATA III drive is the same because the mechanical drives currently available are unable to fill that bandwidth.
SATA III standard is only really important for SSD drives. Some of the newer SSD's are capable of approaching filling of that pipeline, but mechanical drives are nowhere near. Bottom line is, even if you find you are unable to return the drive, the SATA speed won't hurt you performance wise. But typically the SATA 3 drives are pricier, so you are paying for something you didn't receive.