Sounds suspicious hard disk, metallic and shutdown dummy

[pancham]

Recently I have a hard disk WD Caviar Blue WD6400AAKS. I noticed that every time you hear the noise of light metal type, perhaps come from the head (it is a hypothesis, I do not know).
Also at times, while on a regular basis, you hear a noise as if they cease (but is still on and continues to operate normally), and noise in idle (ie, type of turbine fan) decrease in a perceptible, almost flashy say. This happens even when maybe I'm copying the data inside.
From the test WD Data LifeGuard Diagnostics for DOS shows everything ok.
I never had WD interiors, and everything seems to me almost abnormal.

[Myron]

I read the following on the site of the support that some WD occasional noises are normal:

Current drive technology dictates that some noise will occur during drive operation. The type of noise and the volume of the noise can change depending on the current function that the drive is involved in. It is important to recognize noises which indicated trouble and which are simply normal drive sounds.

Normal drive sounds include:
Whining noise during drive spin-up

Occasional clicks during data access

Hard clicks during a head park operation (shutdown or sleep mode)
Abnormal sounds drive include:
High-pitched whining sound

Vibration sounds either due to vibration in the mounting hardware or in rare cases, a drive failure

Clicking or clunking sounds that occur repeatedly

Grinding sounds
Solutions:

Step1: Make sure it is not a case fan or another device
Turn off the system. Remove both the power and data cables from the drive. Turn on the system to see if the noise continues. If the noise is still present, the drive is not the cause. Search for another device such as a case fan, which is causing the noise. If the noise is no longer present, continue with Step 2.

Step 2: Determine if the problem is the drive or its data cable
Turn off the system. Connect only the power cable to the drive, and turn on the system. If the noise occurs, the problem is with the drive. At this point, continue with Step 3. If the there is no noise, the drive is not at fault. Turn off the system and connect your data cable. Turn on the system. If the noise occurs now, your data cable is faulty and should be replaced.

Step 3: Try the drive in a new location
Turn off the system. Install the drive into a different drive bay or place it securely on an anti-static surface if available. Attach only the power cable. Turn on the system. If the noise is still present, the drive has failed and should be replaced. Information about in warranty replacement options is available in 8 ID Answer: How can I replace a product under warranty?. If there is no noise, the original drive bay was not properly supporting the drive. You will need to mount the drive properly.

I'm not sure I understand all the noises described though. What do you think?

[Arkad]

I have another type of hard disk extension, so I am such a thing makes a noise such as "stock" and then comes off as coming out of their error and then reading again. will contact dell usb?

[pancham]

I have another type of hard disk extension, so I am such a thing makes a noise such as "stock" and then comes off as coming out of their error and then reading again. will contact dell usb?

But mine is internal, not a "stock" and I get errors.