Originally Posted by hammong
I've seen no less than five reputable reviews on the Red that claim variable rotational speed, and the WD specifications on their own site don't list a fixed speed. Who knows, LOL.
That's because those sites are just going by Western Digital's claims regarding IntelliPower (mind you, from memory, even the earliest Caviar Greens were "IntelliPower"). Here's an interesting snippet from Silent PC Review regarding IntelliPower taken from this article
It's quite simple, really. Most of a drive's power is consumed by the motor that spins the disk inside the drive. Reduce the speed of the disk, and you reduce the amount of power required. However, Western Digital doesn't want to say that they're selling 5,400 RPM drives — those became second class in the desktop market years ago. Instead, they rate the drive's speed as "IntelliPower" and take pains to emphasize that there are other factors that affect performance.
Western Digital has caught a lot of flak for withholding the rotation speed of the Green Power, especially when the product was first launched and the marketing material listed the rotation speed as 5,400-7,200 RPM. This led some to speculate that the rotation speed changed dynamically during use — which would have been an impressive engineering feat had it been true. The reality is revealed by a sentence that Western Digital added to the description of IntelliPower: "For each GreenPower™ drive model, WD may use a different, invariable RPM." In other words, Western Digital reserves the right to release both 5,400 RPM and 7,200 RPM drives under the Green Power name — without telling you which are which.
We were able to confirm that our 750 GB Green Power had a spindle speed of 5,400 RPM by analyzing its sound spectrum. Why sound? Sound is vibration; the pitch of the sound corresponds to the frequency of the vibration. Hard drives vibrate at the speed of their motor, so they produce a noise at the same frequency as their rotation speed. Our sample had a sharp spike at exactly 90 Hz (cycles per second). Multiplying that number by 60 (to get cycles per minute) yielded a measured rotation speed of 5,400 RPM.
This little Frequency / Amplitude graph tells us the WD Green drive spins at 5,400 RPM.
It's possible that other Green Power models use a higher spindle speed — but we doubt it. Storage Review tested the 1 TB version of the drive and determined that that model also spun at 5,400 RPM based on a calculation of the drive's latency compared to a previous Western Digital model. That leaves the 500 GB model — which Western Digital says is even lower power than the larger capacity versions. With the majority of the Green Power's efficiency advantage coming from its lower speed, it seems impossible for the 500 GB model to use a higher rotation speed. It's possible Western Digital intends to release a 7,200 RPM version at some point in the future.
Originally Posted by hammong
So you're saying that the Red and Green have different mechanisms internally - and not just different firmware. I think the performance differences shown in the Xbitlabs review are more about performance optimization vs. power savings, and the fact that the Red is performance optimized (while still being reduced rotational speed vs. Black) and the Green is power consumption optimized.
Both the Reds and the Greens are optimized for power consumption. The Red just happened to be using newer 1TB platters vs I believe 750GB platters on the Green. The 1TB platter is pretty much the same reason why the WD Blue 1TB WD10EZEX performs better than WD Blacks despite having the same rotational speed. If you compare the WD Red 3TB WD30EFRX with the WD Green 3TB WD30EZRX
which also uses 1TB platters, performance is very similar. Another thing, if the WD Red had variable rotational speed and really did go up to 7200RPM, we should have seen performance that's the same as the WD Blue 1TB. The fact that we haven't suggests it still uses 5400RPM same as all the drives that came before it.
Fixed links.Edited by rui-no-onna - 7/9/13 at 7:26am