A hard drive that has started clicking, ticking or knocking is telling you something has gone wrong inside it. It is one of the most common reasons people contact our lab, and it is also the situation where what you do in the next few minutes matters most. This guide explains what the sound usually means, why leaving the drive running is risky, and what to do instead.
What the clicking usually means
Inside a hard drive, read/write heads float a few nanometres above spinning platters. When the drive powers up, the heads move out over the platters and try to read the drive’s own service information. If they can’t, the drive retracts them and tries again – and that repeated sweep-and-retract is the click you hear.
The most common causes are:
- Failed or weak read heads – often after a drop or knock, but sometimes simply through wear.
- Damage to the platter surface – scratches or degraded areas where the heads can no longer read.
- Firmware or service area problems – the drive’s internal data is corrupted, so it cannot finish starting up even though the mechanics are fine.
- Not enough power – especially with portable USB drives on a weak port or a damaged cable. This is the one cause you can safely rule out yourself.
Why you should switch it off
If the heads are damaged, every power-on drags them across the platters again. Damaged heads can scrape the magnetic surface where your data lives, and once the platters are scored, parts of that data can be lost permanently. A drive that clicked for a few seconds is usually a far better recovery prospect than one that was left clicking for hours while someone tried different computers.
Things not to do
- Don’t keep plugging it in to “see if it works now”. Each attempt is another chance for further damage.
- Don’t run recovery or repair software. Software can’t fix a mechanical fault and puts the drive under heavy, continuous load.
- Don’t put the drive in the freezer, tap it or shake it. These old tricks cause condensation and more physical damage.
- Don’t open the drive. Heads and platters are handled in a clean room for a reason; a single speck of dust can destroy a platter surface.
What you can safely check
If it is an external USB drive, try once with a different, short USB cable plugged directly into the computer (not a hub), and if it has its own power adapter, make sure that is connected. If it still clicks, power it off and leave it off. For a drive inside a laptop or desktop, simply shut the computer down.
How a clicking drive is recovered
In our lab the drive is first diagnosed to find which part has failed. Where the heads are faulty, a matching donor head assembly is fitted in clean conditions. The drive is then imaged sector by sector on specialist hardware that reads weak areas gently and skips past damage so the readable data is secured first. Your files are recovered from that image, never from the original drive, and copied to a new drive for you.
See our hard drive data recovery and external hard drive recovery pages, or call 020 7394 2525 before you try anything else. You can bring the drive to our lab at Unit 1, 80 Willow Walk, London SE1 5SY, or arrange a courier collection.