For most US buyers, 2TB is the practical default for a primary M.2 SSD; 4TB pays off only if you keep a large game library, 4K media, or virtual machines on one drive.
A single large game can swallow 150GB; two of those plus Windows and a photo library make 2TB tight. Capacity alone won’t make anything faster — the choice comes down to how much you store, how often you archive, and the price gap on the exact model you want.
What Decides Whether 2TB Is Enough?
For most people, 2TB covers Windows, everyday apps, a good-sized game library, and ordinary photo or video work — if you’re willing to uninstall or archive occasionally. It’s also the sensible starting point for a system drive, since faster capacity tiers rarely improve real-world speed.
- Windows, macOS, or Linux boot drive plus office and creative apps.
- Substantial photo libraries and one or two active video projects.
- Ordinary gaming — a handful of installed titles, not a permanent collection.
- Anyone already using external storage or cloud archives for cold files.
If that sounds like you, the extra money for 4TB buys headroom you’ll rarely use.
When Does 4TB Actually Pay Off?
4TB earns its price when you refuse to shuffle files: many large games installed at once, multiple 4K or 8K projects, virtual machines, local AI models, or big RAW media libraries. It also makes sense in a laptop or small desktop with only one practical drive bay, where adding storage later means opening the machine or carrying an external drive.
Two hard truths apply to both sizes:
- An SSD is not a backup. A second partition won’t protect you from drive failure, theft, ransomware, or a bad delete. Keep a separate backup destination.
- Don’t fill it to the brim. Leave free space for OS updates, temporary files, and sustained write performance. No single reserve percentage fits every workload.
A concrete example makes the price gap easier to judge. Samsung’s US listings for the 990 PRO show both capacities share the same PCIe 4.0 x4 interface and 7,450MB/s sequential read rating — so the 4TB buys room, not speed.
Compatibility And Setup: Where Buyers Trip Up
The Samsung 990 PRO requires an M.2 2280 slot that supports PCIe/NVMe — an M.2 slot that only runs SATA will not work, and the physical slot alone doesn’t guarantee compatibility. Check your computer or motherboard manual for supported keying, PCIe generation, boot support, maximum capacity, and whether installing the drive disables another SATA or PCIe slot.
- Capacities aren’t exact. Samsung notes usable capacity is lower than advertised after decimal calculation, formatting, partitioning, and system overhead.
- Heatsinks add height. Samsung lists the heatsink version as PS5 compatible, but the added height must clear your console or motherboard cover.
- Bare drives need clearance checks. If installing under a motherboard heatsink, verify thermal-pad contact and follow the manufacturer’s instructions.
- Power draw differs slightly. Samsung reports roughly 5.5W average and 8.5W maximum for 2TB versus 6.5W average and 8.6W maximum for 4TB — worth noting in thermally tight laptops.
Setup is straightforward once installed:
- Back up important data before replacing or migrating a drive.
- Shut down, unplug power, and follow static-electricity precautions.
- Seat the SSD at the connector angle, secure it, and fit a compatible heatsink if needed.
- In Windows, open Disk Management, initialize the drive, choose GPT for modern UEFI systems, create a volume, format it, and assign a drive letter.
- Update firmware only through the manufacturer’s supported software.
When it works, the drive appears in File Explorer with its full, usable capacity and a drive letter ready to use.
If you’ve already decided 4TB is the right call, our tested roundup of 4TB M.2 SSDs compares the current options worth buying.
Which Capacity Should You Buy?
Buy 2TB if you keep a manageable library and don’t mind clearing space occasionally; buy 4TB if your drive is the only place large files can live. Samsung’s full specifications for the 2TB 990 PRO show what the practical tier delivers.
The deciding question: how much of your data is genuinely hard to archive? If the answer is “very little,” 2TB is the smarter buy. If it’s “most of it,” 4TB stops being a splurge and starts being cheaper than the time you’d spend managing space.
FAQs
Is a 4TB SSD faster than a 2TB one?
Not necessarily. Samsung’s 990 PRO lists the same 7,450MB/s sequential read and 6,900MB/s sequential write ratings for both capacities. The 4TB model slightly edges ahead in random read IOPS — up to 1,600,000 versus 1,400,000 for 2TB — but for everyday tasks the difference is hard to notice. Capacity buys room, not a speed upgrade.
Will a 4TB drive show the full 4TB in Windows?
No. Samsung states usable capacity is lower than advertised because of decimal capacity calculation, formatting, partitioning, operating system overhead, and installed applications. Windows typically reports a smaller figure than the number on the box, and that applies to 2TB drives as well. This is normal, not a fault.
Can I add a second drive later instead of buying 4TB now?
Only if your machine has a free M.2 slot that supports PCIe/NVMe or another open drive bay. Many laptops and some small desktops have just one practical slot, which is exactly when buying 4TB up front makes more sense than paying for a swap later.
References & Sources
- Samsung Electronics. “2TB PCIe 4.0 NVMe M.2 SSD 990 PRO” Supplies 2TB capacity, speed, DRAM, and power figures cited above.
- Samsung Electronics. “4TB PCIe 4.0 NVMe M.2 SSD 990 PRO” Supplies 4TB speed, IOPS, DRAM, and list price figures cited above.