TechARP posted a review on the Western Digital RE4-GP 2 TB Hard Disk Drive

The biggest difference between the Western Digital RE4 hard disk drive and the Western Digital RE4-GP hard disk drive is the spindle speed. The "regular" RE4 drive spins at 7,200 RPM while the RE4-GP spins at a slower fixed speed between 5,400 RPM and 7,200 RPM. Everything else remains identical between the two drives.

Although the WD RE4-GP may appear to be a RAID-optimized version of the WD Caviar Green desktop hard disk drive, it is far more than just the Caviar Green with TLER support. Let's find out just how well it performs against the 10,000 RPM WD VelociRaptor and other leading desktop hard disk drives.

Western Digital RE4-GP 2 TB Hard Disk Drive Review