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A 2TB hard drive costs about £45. A 2TB NVMe SSD costs about £100. They hold exactly the same amount of data, they connect to the same motherboard, and only one of them will make an eight-year-old laptop feel new again.
The SSD vs. HDD decision really comes down to three questions: how fast you need the data, how much of it you’re keeping, and how often it gets written. Everything else is detail.
What’s Actually Inside Each Drive
A hard disk drive stores bits on magnetic platters spinning at 5,400 or 7,200 RPM, with a read/write head on an actuator arm floating a few nanometres above the surface. It’s beautiful precision engineering, and it’s mechanical, which means the drive has to physically wait for the right sector to rotate underneath the head.
A solid-state drive has no moving parts. Data sits in NAND flash cells, and a controller decides which cell to read or write. Access is electrical, so nothing has to spin into place first.
That one difference explains nearly every trade-off below.
Speed Beyond the Big Sequential Numbers
Manufacturers love sequential read figures, because that’s where the numbers look best:
- 7,200 RPM 3.5-inch hard drive: roughly 150–250 MB/s
- SATA SSD: roughly 500–550 MB/s
- PCIe 4.0 NVMe SSD: roughly 5,000–7,000 MB/s
Those numbers genuinely matter when you’re copying a 60GB video project or cloning a drive. For everyday work they matter far less than random access, and that’s where the gap turns brutal.
A 7,200 RPM drive manages somewhere around 75–150 random IOPS. A SATA SSD handles 10,000–40,000. A good NVMe drive can pass half a million. Windows loading a few hundred small system files is a pure random-read workload, which is why a £40 SATA SSD can cut a boot time from 90 seconds to 15 on hardware that otherwise hasn’t changed at all.
What that feels like in practice
- Cold booting Windows: 15–25 seconds on SSD, 60–90+ on HDD
- Opening Photoshop: 3–5 seconds versus 20–40
- Loading a big game level: 10–20 seconds versus 40–90
- Searching a folder of 200,000 photos: near-instant versus go and make a cup of tea
Price Per Terabyte, and Why the Gap Is Narrower Than You’d Guess
Street prices move around, but the shape of the market is stable. An 8TB CMR hard drive runs about £140, or roughly £17 per terabyte. A 1TB SATA SSD is around £55, and a 2TB NVMe drive around £110, which works out at about £55 per terabyte for both.
Here’s the bit people miss: SSD cost per terabyte barely improves as capacity grows. A 4TB NVMe drive at roughly £220 is still about £55 per terabyte. Hard drives get dramatically cheaper the bigger they get, which is the entire reason they still exist — a 20TB model lands near £15 per terabyte.
Where spinning disks still make sense
Cold data. Photo and video archives. Media libraries. Backups that get written once a week. Security camera footage. Bulk Steam libraries on a tight budget. Anything where you care about capacity and price far more than latency.
Endurance, Noise, Heat, and the Specs People Skip
SSDs wear out from write exhaustion, which sounds alarming until you do the maths. A 1TB TLC drive rated at 600 TBW could take 100GB of writes every single day for around 16 years. Controller failures happen first in reality, and most drives outlive the machine they’re installed in.
Hard drives fail differently — head crashes, shock damage, bearing wear. A 30cm drop while the platters are spinning can kill one outright. An SSD won’t notice it.
Power and noise are worth a thought if the machine lives in a bedroom or a living room. A 3.5-inch drive pulls 6–9W when working and produces a constant 25–30 dBA hum with occasional clicks. A 2.5-inch SSD draws under 3W and makes no sound whatsoever.
Two specs deserve a check before you pay. On SSDs, find out whether there’s a DRAM cache — DRAM-less drives slow down sharply on sustained writes once the SLC cache fills. On hard drives, check whether the model uses CMR or SMR recording. SMR is fine for cold storage and genuinely awful for sustained writes or RAID rebuilds.
Matching the Drive to the Job
- Boot drive in any desktop or laptop: an NVMe SSD, 500GB to 1TB. There’s no argument for a hard drive here in 2025.
- Game library: a 2TB NVMe drive if the budget allows, since newer titles use direct storage paths that reward fast drives. A SATA SSD is a perfectly fine second choice.
- Photo and video archive: a 3.5-inch hard drive, ideally two of them in different rooms.
- NAS or home server: CMR drives rated for 24/7 use, mirrored in pairs. Don’t build a RAID array on SMR disks.
- Reviving an old laptop: a £35 500GB SATA SSD is the best money you’ll ever spend on it.
- Laptop with a single drive slot: one large NVMe drive beats juggling two smaller ones.
The Two-Drive Setup Most People Should Actually Build
A small fast SSD for the operating system, applications and whatever you’re working on right now. A big slow hard drive for everything that doesn’t care about latency. A 1TB NVMe plus an 8TB hard drive costs around £200 total and covers almost every realistic workload.
Configuring it properly takes ten minutes. Move the default Documents, Downloads and Pictures folders to the hard drive. Add a second Steam library folder there so games you’ve finished stop hogging SSD space. Keep the Lightroom catalogue and previews on the SSD but point the raw files at the hard drive — you get fast browsing and cheap bulk storage. Leave the page file on the SSD, where it belongs.
The one thing to avoid is putting a database, virtual machine, or anything doing constant small writes on the spinning disk. That’s exactly the workload hard drives are worst at.
What to Check Before You Click Buy
For an SSD, confirm the M.2 slot keying and length — most are M-key 2280, but plenty of compact laptops take 2230 drives, and the wrong size simply won’t fit. Check whether the slot runs at PCIe 3.0 or 4.0, since a Gen 4 drive in a Gen 3 slot is a waste of money rather than a problem. On some motherboards, populating an M.2 slot disables two SATA ports, which matters if you’re keeping your old drives.
For a hard drive, check the RPM, whether it’s CMR or SMR, the workload rating, and the warranty length. A three-year warranty versus five tells you a lot about how the manufacturer expects the drive to be treated.
Buy the fastest thing you can afford for whatever you touch every day, and the cheapest per terabyte for whatever you touch twice a year. That single rule gets almost everyone to the right answer.
