WD provides a data sheet with the power and noise specs for their individual drives. If you are buying to use in a situation where these matter shouldn't you be consulting the published specs instead of just choosing 5400 vs 7200? After all these can be greatly variable even between drives of the same RPM.

I mean... doesn't that same sheet of published specs state that it's running at 5400 RPM?

If they lie about that on their spec sheet, how can you believe the power/noise levels written on there?

Also, I've always had a fair amount of scepticism for digital product spec sheets. I've been looking for a projector with low input lag for a while, and the measured value has constantly been way off the claimed value (> factor of 2). Admittedly, this seems to most often be the case with some of the cheaper chinese brands, but definitely not exclusively.

They don't actually claim it is running at 5400 RPM. They claim performance is in the 5400RPM performance class. In other words it will perform similar to a drive running at 5400RPM. Nowhere do they mention that it runs at 5400RPM.

I stand corrected, you're right. Ref from link

> Looking at the spec sheets provided by WD, it seems they don't really list the rotational speed

I still think it's somewhat disingenuous, but my comment above was wrong.

According to the linked post, "5400rpm class" was a lie too.