Speeds slower than expected? Here is why.
If your Sabrent drive starts fast then slows down, or is not reaching the speeds you expected, this guide covers the most common causes.
The most common cause: SLC cache behavior (fast then slow)
If your drive starts a transfer at high speed and then drops noticeably after a few seconds to a few minutes, your drive is working exactly as designed.
Here is what happens: your SSD uses a portion of its memory as a high-speed write cache. When you start a large transfer, data lands in that cache at peak speed. Once the cache fills during sustained writes of several gigabytes, the drive switches to its base write speed, which is slower. After the transfer finishes and the drive sits idle for a bit, the cache speed comes back.
This is standard for this type of SSD. Every manufacturer's drive of this class works the same way. For everyday use (installing apps, loading games, working with files), you will almost always stay within the cache and see full speed. The slowdown only appears during sustained multi-gigabyte writes.
USB 2.0 vs USB 3.0 (capped around 35 to 40 MB/s)
If your speeds are stuck around 35 to 40 MB/s, you are likely connected through a USB 2.0 port or cable.
- USB 3.0 ports are usually blue inside; USB 2.0 ports are black. On a desktop, look for the blue ports on the back of the tower.
- Make sure the cable is USB 3.0 as well. An older USB 2.0 cable will limit speed even on a 3.0 port.
- If you are going through a USB hub, try connecting directly to the computer instead.
Hub or dock bottleneck
USB hubs share bandwidth across all connected devices. If other devices are plugged into the same hub, they compete for speed. Try connecting your drive directly to a USB port on your computer and run the same transfer. If speed jumps up, the hub was the bottleneck.
Thermal throttling
If the drive slows down during sustained use and recovers after a break, it may be protecting itself from overheating.
- Make sure the drive or enclosure has airflow. Do not set it on a blanket, cushion, or in a closed space.
- For internal NVMe drives, a heatsink makes a real difference.
- Aluminum enclosures dissipate heat better than plastic ones.
Nearly full drive
SSDs slow down when they are over about 90% full. The controller has less room to manage data efficiently. Check your free space and try freeing up 10 to 15% of total capacity.
Drive health
If none of the above applies and speeds are still below what you would expect, check the drive's health using CrystalDiskInfo (Windows) or DriveDx (macOS). If the health status shows "Caution" or the Total Bytes Written is near the rated limit, the drive may be reaching end of life.
Still need help?
If you have checked all of the above and your speeds are still below your product's rated spec, contact our support team with your product model and the speeds you are seeing. We will take a closer look.