How to Choose an SSD: Speed, NAND, Endurance and Capacity

For most PCs, buy a PCIe 4.0 TLC drive of at least 1 TB, and 2 TB if you keep a real game library installed. That covers boot, apps and games with no compromise you will notice. SSD prices are far above where they launched, so this is a poor year to pay extra for a sequential speed number you will rarely reach.

PCIe generations and when they matter

Sequential speed is the number on the box, and it is the least useful one for everyday use. Launching apps and loading games depends mostly on small random reads at low queue depth, and Tom's Hardware's 1 TB charts show the fastest drive only about 70 percent quicker than the slowest in that metric. Sequential speed matters more for drive-to-drive copies, backups and installing or verifying large games, where the top performers can be several times faster.

Games using DirectStorage need an NVMe SSD, and Microsoft's requirement stops there. PCIe 5.0 is not on it.

Here is the rule. If a PCIe 5.0 drive costs within about 10 percent of an equivalent PCIe 4.0 drive, and your board has a PCIe 5.0 M.2 slot that does not take lanes from the graphics card, buy it. On November 9, Samsung's PCIe 5.0 9100 Pro 2 TB cost only a few percent more than its PCIe 4.0 990 Pro 2 TB, so the choice is close at times. When the gap is wider, buy PCIe 4.0. Our PCIe lanes explainer and motherboard guide explain which slots share lanes.

DRAM vs DRAM-less

A DRAM cache holds the map of where data lives on the drive. DRAM-less drives keep that map in a small slice of your system memory instead, through a feature called Host Memory Buffer, and modern controllers make this work well. Many strong drives skip DRAM, including the Samsung 990 EVO Plus, Lexar NM790, TeamGroup MP44 and SanDisk Optimus GX 7100, all TLC. Tom's Hardware treats the lack of DRAM as a minor point on budget drives.

Pay for DRAM when the drive will spend its life nearly full or handle heavy mixed reads and writes, such as a scratch disk or a boot drive on a busy workstation. The Samsung 990 Pro and SanDisk Optimus GX Pro 850X are examples. DRAM-less drives also tend to use less power, which matters more in a laptop than a desktop.

TLC vs QLC

TLC stores three bits per cell and QLC stores four. QLC is denser and usually cheaper, but it wears faster and slows down sharply once its fast cache fills. That makes it fine for data you mostly read, such as a game library, and a poor choice for anything that writes constantly.

Some prebuilts use QLC to hit a price, so check before you assume. If a drive's listing does not say, look up its review.

Endurance

Endurance is rated in terabytes written, or TBW. A typical 2 TB TLC drive in our SSD category is rated around 1,200 TBW, with the Lexar NM790 at 1,500 and the TeamGroup MP44 at 1,000. One popular 2 TB QLC drive is rated at 440 TBW.

Do the math for your own use. At 50 GB written a day, 440 TBW lasts more than 24 years, so normal users will never get close. At 500 GB a day, as on a busy video scratch disk, the same drive would hit its rating in under two and a half years. Most warranties run five years or until the TBW limit, whichever comes first. If you do not know how much you write, your drive's monitoring tool will tell you the total so far.

Capacity planning

Start with what you already use, then add room. Windows and core apps take a modest share, but large games commonly run past 100 GB each, and modern titles keep growing.

• 1 TB: The minimum for a gaming PC, enough for several large titles.
• 2 TB: The practical target for most gaming builds.
• 4 TB: Usually better split into two drives right now.

On November 9, Samsung's 990 Pro cost about 2.8 times as much at 4 TB as at 2 TB, so two 2 TB drives were cheaper than one 4 TB drive with the same controller. If your board has a second M.2 slot, buy what you need today and add another later. Our M.2 install guide shows how.

Keep 10 to 20 percent of the drive free. SSDs use spare space for their fast cache and for wear leveling, so a nearly full drive feels slower. For bulk media and backups, a hard drive, NAS or external drive costs far less per terabyte.

Heatsinks

PCIe 5.0 drives run hot and need cooling. Corsair says the MP700 Pro requires it to reach its rated speeds, and Samsung's 9100 Pro runs warm under load, so a bare drive needs a motherboard heatsink or good case airflow. Most PCIe 4.0 drives are comfortable under a basic motherboard shield.

Use one heatsink, not two. Most ATX boards include a shield for at least the main slot, so a drive with its own heatsink can be wasted or may not fit. Heatsink versions are also thicker: SanDisk's 850X goes from 2.3 mm bare to about 9 mm with a heatsink, and WD's SN8100 from 0.09 inches to 0.38 inches. Check clearance under the graphics card and around large air coolers, and read your board's manual, since some models such as the MSI MEG Z890 Ace note heatsink restrictions on specific slots.

Boot, game and scratch drives

SATA once meant savings, but on November 9 the Samsung 870 EVO 2 TB cost more than the much faster 990 Pro 2 TB. Buy it only when your PC cannot take NVMe.

One drive is fine for most people. A separate scratch or capture drive earns its place when you edit video or record gameplay, because it keeps constant writes off the disk Windows runs from. See current picks when you are ready to buy, and read our memory guide if you are budgeting for both during the shortage.