C Drive Full: Compress Windows or Add an SSD in 2026? What Linus Tech Tips Shows (and the NVMe SSDs Worth Buying)

Is your C drive in the red? Here is what actually works on Windows 11 and Windows 10, in order:

1. Clean up with the Windows tools: Storage Sense, Cleanup recommendations and Disk Cleanup (with “Clean up system files”). It is risk-free and often the most effective step.
2. Reclaim the big system files: hibernation turned off or reduced, the old Windows.old folder after an update, component cleanup with DISM.
3. Compress Windows the right way with Compact OS: a few gigabytes gained, at the cost of a little CPU work. Never by archiving the Windows folder with WinRAR or 7-Zip.
4. Add a 1 or 2 TB NVMe SSD: it is the only lasting fix. SSD prices move fast right now, so check the live price in each product box below.

Our SSD picks: the WD_BLACK SN7100 for games and heavy writes, the Kingston NV3 on a budget, the Samsung 990 and the Crucial P310 for a laptop, and the WD Green SN3000 2 TB for capacity. If you just want the best 1 TB drive, our 1 TB M.2 SSD guide compares more models.

On October 20, 2026, Linus Tech Tips published “I Gotta Stop Following Advice From Reddit”. The starting point: a Reddit user who was running out of space right-clicked the Windows folder and chose “Add to archive” in WinRAR. The team repeated the experiment to see what happens.

• WinRAR lets you do it: it only complains about the few dozen system files that are in use, and compresses everything else.
• With the wrong options, it is a disaster: WinRAR can automatically delete the files it has just archived. System files stored inside a .rar can no longer be used by Windows.
• The video’s verdict: the user had “the right idea, but the wrong tool”. What they were probably looking for was Compact OS, the compression built into Windows 10 and 11.

The video also explains why the idea is not absurd. Back in the days of DOS and early Windows, software like Stacker compressed the whole drive and roughly doubled the usable space. But it concludes that on a modern PC, compression only buys you a short reprieve: enough time to order a bigger drive.

Key takeaway: never archive, move or delete files in C:\Windows, and especially in the WinSxS folder. Microsoft says so explicitly: deleting files from WinSxS can stop your PC from booting or updating.

Lossless compression spots repetitions in a file and replaces them with shorter references. That is the principle behind the LZ (Lempel-Ziv) family of algorithms used in ZIP, PNG and RAR. The problem: most of what fills a drive in 2026 is already compressed.

• Office documents: a .docx file is actually a ZIP archive in disguise, as the video points out.
• Photos, music and videos: JPEG, MP3, AAC and MPEG use lossy compression. Compressing them again gains almost nothing.
• Games: their assets are often already packed and compressed by the engine.
• Small files: a drive stores data in blocks (4,096 bytes on current drives, versus 512 in the past). A small file usually takes up a whole block, compressed or not.

That is why Compact OS is not enabled by default: the gain is real but limited, and decompression asks the CPU for a little work on every read.

Compact OS compresses the Windows files themselves, transparently: the system keeps working normally and decompresses what it reads on the fly. The tool ships with Windows 10 and Windows 11 as the command compact.exe. Microsoft notes that Windows Update can replace compressed files to keep the system footprint under control.

Open Terminal or Command Prompt as administrator, then type:

compact.exe /CompactOS:query

Windows tells you whether the system is already compressed. On some devices with small storage, it may already be active.

compact.exe /CompactOS:always

The operation takes anywhere from a few minutes to longer depending on the drive and CPU. Keep the PC plugged in and do not turn it off during compression.

compact.exe /CompactOS:never

How much does it save? Linus Tech Tips gives no figure. The only official reference comes from Microsoft: on 64-bit Windows 10 version 1607 with 4 GB of RAM, Compact OS shrinks the system footprint from about 15.06 GB to 11.3 GB, recovering more than 3.7 GB. That figure is dated and varies with the Windows version and what is installed: treat it as a ballpark, not a promise.

The same command can compress a specific folder, such as an installed game, using the option /EXE and an algorithm of your choice: XPRESS4K (default), XPRESS8K, XPRESS16K or LZX, from fastest to most compressed. Example, from an administrator terminal:

compact.exe /c /s:"D:\Games\MyGame" /i /EXE:XPRESS8K

The gain depends heavily on the game: some compress well, others barely at all because their files already are. Files are decompressed automatically if the game modifies them during an update, so you then need to run the command again. Never apply it to the Windows folder: for that, use /CompactOS and nothing else.

• A bit more CPU work: negligible on a recent PC, more noticeable on an old CPU or an entry-level laptop.
• A one-time gain: you recover a few gigabytes once. If your drive fills up with games or videos, it will be full again within a few weeks.
• Nothing beats a proper cleanup: temporary files, hibernation or an old Windows.old often weigh more.

Before compressing anything, start with these steps, all documented by Microsoft. They are ordered from simplest to most technical.

Go to Settings > System > Storage. Turn on Storage Sense: with the default settings, it runs when space is low, deletes unnecessary temporary files and empties the Recycle Bin on the schedule you choose. The Downloads folder is only touched if you enable it yourself. Just below, Cleanup recommendations lists large files, unused files, files already synced to the cloud and apps you no longer open.

Type “Disk Cleanup” in search (or run cleanmgr), choose the C drive, then click Clean up system files. That is where leftover update files live and, after a Windows upgrade, the previous installation.

After an upgrade, Windows keeps the previous version in the Windows.old folder so you can roll back for 10 days. Once everything works, you can delete it via Cleanup recommendations or Disk Cleanup. Warning: this is irreversible, you will no longer be able to go back to the previous version.

The file hiberfil.sys is used for hibernation and Fast Startup. Its size grows with the amount of RAM. In an administrator terminal:

• powercfg /h /type reduced: shrinks the file by about 30% while keeping Fast Startup.
• powercfg /h off: deletes the file, but also hibernation and Fast Startup.

On Microsoft’s test configuration (4 GB of RAM), turning off hibernation frees more than 1.5 GB. With 16 or 32 GB of RAM, the file is much bigger, so the gain is too.

Never delete anything by hand in WinSxS. Windows can clean it up by itself through a scheduled task, and you can run the cleanup yourself:

Dism.exe /online /Cleanup-Image /StartComponentCleanup

The option /ResetBase squeezes out a bit more space, but Microsoft warns that afterwards, updates already installed can no longer be uninstalled. Keep it for a stable PC.

In Settings > System > Storage > Advanced storage settings > Where new content is saved, you can send new apps, documents, music or videos to another drive. With OneDrive, Files On-Demand keeps your files in the cloud and only downloads them when you open them. Game launchers (Steam, Epic, Xbox) also let you move an installed game to another drive.

Microsoft mentions a special case: if the Temp folder fills up with Microsoft Store files, the command wsreset.exe resets the Store cache.

The figures quoted come from Microsoft’s documentation, on its test configuration. On your PC, the real gain depends on your Windows version, your RAM and what you have installed.

Compressing and cleaning up buys time. Adding an SSD fixes the problem. Go straight to the SSD if:

• Your C drive is 256 GB or smaller: between Windows, updates and two or three recent games, it will always be full.
• You have already cleaned up: if the drive fills up again within a few weeks, it is a capacity problem, not a cleanup problem.
• You play games: recent games easily exceed 100 GB each and compress poorly.
• Your PC has a free M.2 slot: it is the simplest and cheapest upgrade for a desktop PC, and many laptops have a second one.

Good news: on a desktop PC, there is no need to reinstall Windows. A second SSD works as a storage drive for games and files, and the C drive can breathe again. SSD prices are still trending up in 2026 because of NAND, as we explain in our tracker of SSD prices in 2026: waiting probably will not lower the bill.

The five models below are M.2 2280 PCIe 4.0 SSDs, the format used by the vast majority of recent desktops and laptops. Specs come from the manufacturers’ data sheets, and the current price appears in each product box.

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For games and heavy writes, start with the WD_BLACK SN7100. It is the only TLC model in the selection, with the best endurance (600 TBW). If you install your games on it, edit video or often copy large files, it is the safest choice. Our best gaming SSD guide compares it with other models for PC and PS5.

The NV3 is the most affordable 1 TB drive in our catalog at the time of writing. Its 6,000 MB/s read speed is more than enough for Windows, apps and games, and its single-sided form factor fits most laptops.

Two DRAM-less SSDs, fast and frugal, so well suited to a laptop where battery life and heat matter. The Samsung 990 offers better endurance (400 TBW versus 220), the Crucial P310 a longer warranty (5 years versus 3). Our laptop SSD guide helps you check your model’s compatibility.

If your problem is mainly capacity, the 2 TB SN3000 is the most sensible option in the selection. It is slower and less durable than the others, but for storing games or photos, that does not matter. For other, faster 2 TB drives, see our 2 TB NVMe SSD guide.

All data comes from the manufacturers’ data sheets. TBW (terabytes written) indicates the rated endurance: the higher it is, the better the SSD handles intensive writes. To understand the difference between TLC and QLC memory, our guide to SSD types covers it. The second table sums up which models fit which segment; SSD prices are moving fast right now, so rely on the price shown in each product box.

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1. Check your motherboard or laptop: number of free M.2 slots, 2280 form factor and NVMe PCIe support. A PCIe 4.0 SSD works in a PCIe 3.0 slot, just at 3.0 speed (see our guide to PCIe 4.0 SSDs).
2. Shut down and unplug the PC, then touch a metal part of the case to discharge static electricity.
3. Insert the SSD at an angle into the M.2 slot, push it down and secure it with the screw or clip provided. Put the motherboard heatsink back on if there is one.
4. Initialize the drive in Windows: right-click Start > Disk Management, initialize the new SSD as GPT, then create a simple volume.
5. Move what takes up space: game libraries, Videos and Downloads folders, and set the location for new content to the new drive.

Would you rather replace the C drive with a bigger one? Then you need to clone the old SSD to the new one with the manufacturer’s tool or cloning software, or do a clean reinstall of Windows. On a laptop with a single slot, it is the only option.

No. Windows cannot read its own files inside an archive, and with certain options WinRAR can even delete the files it has just archived. To compress Windows, use compact.exe /CompactOS:always guide.

Decompression asks the CPU for a little work. On a recent PC, the difference is rarely noticeable; on an old CPU, you may feel it. You can roll back at any time with compact.exe /CompactOS:never guide.

Microsoft cites more than 3.7 GB on 64-bit Windows 10 version 1607. It is a ballpark: the real gain depends on your Windows version. The Linus Tech Tips video gives no figure.

No, never. Use Dism.exe /online /Cleanup-Image /StartComponentCleanup instead, or let Windows’ scheduled task take care of it.

1 TB is enough for Windows, apps and a few games. If you play a lot or store videos, go for 2 TB.

Yes, the M.2 NVMe format is backward compatible: it will run at PCIe 3.0 speed. Just check that the slot supports NVMe and not only SATA.

The Linus Tech Tips video makes it clear: wanting to compress Windows is not a crazy idea, but archiving the Windows folder with WinRAR is the worst way to do it. First clean up with Storage Sense and Disk Cleanup, reclaim hibernation and Windows.old, then turn on Compact OS if you urgently need a few gigabytes. After that, add an NVMe SSD: the Kingston NV3 on a budget, the WD_BLACK SN7100 for games, the Samsung 990 or Crucial P310 for a laptop, and the WD Green SN3000 if you want 2 TB.