Running out of storage space is one of the most common PC problems in 2026. Modern AAA games consume 50–150GB each, and a 1TB primary SSD fills up faster than most builders expect. The fix is straightforward a second NVMe SSD costs under $100 for 1TB and installs in minutes. The part that makes people nervous is doing it without losing Windows, their files, or their game library.
This how to add second ssd to pc guide covers the entire process: checking whether you have a free M.2 slot, installing the drive, making Windows recognise it, and moving your game library across without reinstalling anything.
Step 1 — Check if you have a free M.2 slot
Before buying anything, confirm your motherboard has an available M.2 slot. Most mid-range and high-end motherboards ship with two to four M.2 slots but one is typically occupied by your primary Windows drive. A second slot is almost always present.
The easiest way to check: power down, remove the side panel, and look at the motherboard surface. M.2 slots are horizontal slots typically located above and below the GPU area, often with a heatsink cover. They’re approximately 22mm wide and between 42–110mm long depending on the slot size. Your existing NVMe drive is almost certainly M.2 2280 — 22mm wide and 80mm long. A second identical drive fits any slot rated for M.2 2280, which covers the vast majority of consumer motherboards.
If you can’t easily see the slots, check your motherboard model in the manual or manufacturer’s website. Search your motherboard name plus “specifications” and look for the M.2 section. It will list how many slots exist, their PCIe generation, and which sizes they support.
One important check: some motherboards share bandwidth between M.2 slots and SATA ports or PCIe slots. When a second M.2 drive is installed, a SATA port or PCIe slot may disable itself. Your motherboard manual’s slot configuration section covers this. For most gaming builds this isn’t a problem but if you’re already using every SATA port, check before buying.
Step 2 — Choose the right second drive
For a game storage drive, you don’t need the fastest NVMe available. PCIe 5.0 speeds deliver no meaningful benefit for storing and loading games compared to PCIe 4.0. A quality 2TB PCIe 4.0 drive in the $389 range is the correct choice fast enough that load times are indistinguishable from your primary drive, at a price that leaves budget for the rest of your build.
The Samsung 990 Pro 2TB and WD Black SN850X 2TB are the premium picks. The Crucial P3 Plus 2TB is the value pick at the lower end of the price range slightly slower sequential speeds but imperceptibly so for game loading workloads.
Check the PCIe generation your second slot supports before buying. M.2 slots are sometimes PCIe 3.0 rather than 4.0, particularly on older boards and secondary slots on some B650 boards. A PCIe 4.0 drive installed in a PCIe 3.0 slot runs at PCIe 3.0 speeds fully functional but without the speed premium you paid for. A PCIe 3.0 drive is the correct and cheaper choice for a PCIe 3.0 slot.
Step 3 — Install the drive
Power down completely. Switch off the PSU at the rear. Unplug from the wall. Press the power button once to discharge residual current.
Remove the side panel. Locate the free M.2 slot it may have a heatsink cover secured by one or two screws. Remove the heatsink by unscrewing it and setting it aside.
Hold the NVMe drive at its edges avoid touching the connector or the chips on either face. Align the notch on the drive’s connector with the key in the M.2 slot. Insert at a shallow angle approximately 30 degrees and push firmly until the connector seats fully. The drive will angle upward when seated. Press the far end down flat and secure it with the single mounting screw that came with the motherboard. Don’t overtighten snug-firm is correct.
Replace the heatsink cover over the drive. Some heatsinks have a thermal pad pre-attached if yours doesn’t, a small piece of thermal pad material between the drive and heatsink improves heat transfer. Most M.2 heatsinks on current motherboards include the pad.
Replace the side panel, reconnect power, and boot normally. Windows will not prompt you during boot it boots from the primary drive as normal.
Step 4 — Initialise the new drive in Windows Disk Management
The new drive is installed but Windows doesn’t automatically make it available. You need to initialise and format it first.
Right-click the Start button → Disk Management. Windows may immediately prompt you with an “Initialise Disk” dialogue when it detects the new unformatted drive. If it does, select GPT (GUID Partition Table) as the partition style GPT is the correct choice for any drive on a modern UEFI system — and click OK.
If the prompt doesn’t appear automatically, find the new drive in the lower section of Disk Management it will show as a black bar labelled “Unallocated.” Right-click on the unallocated space → New Simple Volume. Follow the wizard: accept the default volume size (full drive), assign a drive letter (D: is the conventional choice for a second drive), format as NTFS with default allocation unit size, give it a volume label like “Games” or “Storage,” and click Finish.
Windows formats the drive, assigns the letter, and it appears immediately in File Explorer. The whole process takes under two minutes.
Step 5 — Move your Steam game library to the new drive
Steam handles this cleanly without reinstalling games. Open Steam → Settings → Storage. You’ll see your current Steam library location typically on the C: drive. Click Add Drive at the top and select your new drive from the dropdown. Steam adds it as a secondary library location.
To move existing games: in the Storage settings panel, select a game from the list, click the three-dot menu or the move option, and select your new drive as the destination. Steam moves the game files and updates its internal records. The game launches normally after the move no reinstallation, no downloading again, no reconfiguring.
For new game installs going forward: when Steam asks where to install, select the new drive from the library dropdown. Set it as the default library if you want all new installs to go there automatically — Storage settings → select the new drive → set as default.
Step 6 — Move other game launchers
EA App, Epic Games Store, GOG Galaxy, and Battle.net all handle game library moves differently.
EA App: Go to the EA app → Game Library → right-click a game → Move Game. Select the new drive. The game moves without reinstalling.
Epic Games Store: Settings → Manage → find the game → click the folder icon → change the install location. Epic moves the files and relinks the game.
GOG Galaxy: Right-click a game → Manage Installation → Move. Straightforward.
Battle.net: Battle.net doesn’t have a native move feature. The workaround is to move the game folder manually in Windows Explorer to the new drive, then in Battle.net Settings → Game Install/Update → change the game install directory to the new location, then scan for games. Battle.net will find the moved installation and relink it.
What you can’t easily move — and what to do about it
Windows itself and the applications installed on your C: drive stay there. The second drive is for games and media storage not a Windows migration. Moving Windows to a different drive requires a full clone operation using dedicated software like Macrium Reflect Free or Samsung Data Migration (if both drives are Samsung).
If your C: drive is genuinely full and the problem is Windows plus applications rather than just games, cloning the Windows drive to a larger replacement drive is the correct solution a separate process from adding a second game storage drive.
For most builders, the combination of a 1–2TB primary Windows drive and a 2TB secondary game drive gives ample room for the foreseeable future.