Form factor, interface and rotational speed before the capacity

The best internal hard drives for 2026

A spinning drive inside a desktop is now bought for bulk rather than for speed, and the specification reflects that. Form factor comes first: 3.5-inch drives take the large capacities and want a bay and a power lead, while 2.5-inch drives fit a laptop or a small case and stop well short of the same ceiling. The interface is SATA in nearly every case, on the same connector motherboards have carried for years. Then capacity, and here the arithmetic deserves its own sentence: makers count a terabyte as a thousand billion bytes, while many operating systems display the same drive in units of 1024, so a drive labelled with one figure shows a smaller one on screen. Nothing has gone missing; they are two units for one count of bytes, and this site publishes the figure the maker publishes, in the unit the maker uses. Rotational speed divides the shelf into drives that spin faster and reach data sooner, and drives that spin slower, run cooler and draw less. Cache size smooths bursts of writing. What the drive is specified for appears as a workload rating in terabytes per year and as an MTBF figure in hours, and neither is a promised life; the warranty is a third, separate term with its own conditions. Read also the height in millimetres if the destination is a laptop bay, and the stated acoustic figure, because a drive in a quiet room is heard whenever it seeks. We compare capacity, form factor and height, interface, rotational speed, cache size, stated workload rating, warranty length, stated MTBF, stated acoustic figure and stated idle power.

The ones worth installing

1. 

   Hitachi MegaScale DC 4 TB at 7200 rpm, a title printed twice

   4 TB · 3.5-inch · 7200 rpm · 64 MB cache · SATA 6 Gb/s · one bullet, which repeats the title · no duty figure of any kind

   A four-terabyte drive whose single bullet reprints its title word for word, publishing every mechanical figure and not one figure about what the drive is specified to withstand.

   Best for: A bulk volume in a desktop machine where the drive will not be pushed hard, bought by someone comparing on figures alone and getting the rest from the datasheet.

   ≈ 130 €

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2. 

   Seagate FireCuda 4 TB, the one drive on the shelf that prints CMR

   4 TB · 3.5-inch · 7200 rpm · CMR · 256 MB cache · SATA 6 Gb/s · 300 TB per year workload · 255 MB/s sustained

   A four-terabyte desktop drive that publishes its recording method, its annual workload rating and its maximum sustained transfer rate, and that carries a recovery service where a warranty term would be.

   Best for: A desktop machine that writes a great deal — video work, large game libraries, editing scratch space — where the recording method and the annual duty both need to be known before purchase.

   ≈ £246 / 210 €

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3. 

   TOSHIBA MG06ACA10TEY 10 TB, the largest drive of the batch, on a bare SATA line

   10 TB · 3.5-inch · 7200 rpm · 256 MB cache in the title only · SATA with no rate · one bullet that drops the cache figure

   A ten-terabyte enterprise-capacity drive whose single bullet reprints the title and leaves out the cache, and whose interface is named as SATA without a generation or a rate.

   Best for: A machine that needs the most capacity per bay available here, where the buyer will confirm the interface generation and the duty figures from the datasheet.

   ≈ 300 €

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4. 

   Western Digital Purple Pro 8 TB, 550 TB a year, and no interface at all

   8 TB · 3.5-inch · 7200 rpm · 256 MB cache · 550 TB per year workload · OptiNAND and AllFrame named · interface not published

   An eight-terabyte drive with the highest published workload rating in this batch, whose four bullets say nothing about the product and whose interface is never named.

   Best for: A machine that writes continuously — a recorder, a surveillance store, a busy archive — where the annual duty figure is the deciding line and the interface can be confirmed elsewhere.

   ≈ $400 / £373 / 429 €

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