Western Digital Caviar Green 2TB Hard Drive Review

Under The Hood

Like many newer drives, this hard drive does not use attached cables to move data and power from the PCB to and from the drive itself. Rather, it relies on the perfect placement of the spindle power connections (the hard points near the orange cable in the above picture) and a multi prong data port similar to what is seen in laptops to connect the SATA drive to the motherboard. To ensure proper alignment there are two small plastic alignment posts which have accompanying holes in the PCB.


In the continuing trend of Western Digital frugally reusing as much as possible from one line to another, the PCB which graces the Caviar Green 2TB is a dead ringer for the one found in the Caviar Black 2TB. As we have said before, this is not a bad thing and anything which can help keep prices down has to be considered a good thing. Of course, while the PCB is the same, the components on it are not necessarily going to be.


The cache this drive sports has been boosted from the previous generations 16MB to 32MB and while we are not a proponent of “more is always better” we can understand why Western Digital did this. The reason we are not overly impressed is the difference in performance between 2MB and 8MB was minor, and the improvement from 8 to 16 was even smaller, which means the 16MB to 32MB increase is smaller still.


The external cache module this drive sports is made by Winbond and not Hynix like the Black 2TB has. Normally we would be curious why Western Digital didn’t go with just one supplier for all their lines but the answer is pretty obvious: price.

It is actually interesting that WD decided to go with an external cache module on this drive in the first place. After all, the Black line got along very nicely without one (instead relying on integrated cache on the Marvel SoC) until they went with more than Marvel could offer on their SoC’s: 64MB of cache. In either case and to be more precise, the single Winbond chip is model W9425G6EH-5. This is a 2.5 volt, 256megabit (32MB) DDR SDRAM, TSOP II 66pin chip. Since this is the “-5” version of this model, it means this particular one is rated for a maximum speed of 200mhz @ CL3.


Since this PCB sports an external cache chip, we knew for a fact that it wasn’t going to use the same controller as the Black line. For the time being, a dual processor controller chip still remains the realm of the Black line and only the Black line (though we have a sneaking suspicion the next generation of the Raptor line will probably have one too). Like we said, a single core controller is what we were expecting and that is what we got; however, what we were not expecting was to see the Marvel 88i8945 make another appearance.

We can honestly say we got our hopes up when we saw this chip as it is the same model the 2TB Black uses. Unfortunately, they are not the exact same chip. The Caviar Black 2TB uses the Marvel 88i8945P, whereas the Caviar Green uses the non P version (i.e. just a Marvel 88i8945). As we have said in previous reviews, Marvel is less than forthcoming with information when it comes to their System on a Chip (SoC) controllers. What is known is the P in the Black line obviously stands for Performance (much like the “E” in the previous generations 88i8845 stood for enhanced).

We wouldn’t be overly surprised if this chip also comes with what Marvel calls Tightly Coupled Memory (i.e. onboard memory) but obviously Western Digital felt more comfortable relying on an external solution rather than using it.


Also as expected, the motor controller on the 2TB Caviar Green is made by ST Microelectronics, which is the same manufacturer of all the Western Digital drives we have looked at. To be precise this is a SMOOTH L7251 3.1 controller chip which is not the same as the 2TB Caviar Black’s 3.2 revision of the L7251. However, a slightly earlier revision or not, it is still a damn good controller. The easiest way to understand what this chip does is to look at it this way: if the Marvell chip is the “brain” of this setup then this chip is the Central Nervous System. In a nutshell, this controller is responsible for governing darn near everything related to mechanical and electronic power functions of the Green 2TB.