Then we tried to copy big files from the internal NVME SSD to the Crucial X8 4TB Portable SSD drive to test the writing endurance of the drive. The first test was to copy from a Samsung 980Pro 1TB NVME SSD a 47GB Single file to each Crucial NVME SSD with the Terracopy Software. The writing process was very good, and with no other data written, the whole process was performed with an average of 800-850MB/sec writing speed.

Performing the same test with a single 218GB file, gave us, more or less similar results. The single file was written without any issues and performance was very good, up to 840MB/sec, with no speed drops.

For the third and final test, we did fill up the Crucial X8 4TB Portable SSD with various files and till the 1TB point, the writing speeds were very good, however...we did notice a major drop at the point, where the drive has 1TB of data filled. Then performance drops down to 50Mb/sec, was isn't something that was expected. This has been noted also in other user's feedback after looking at Amazon.com reviews.

After removing the drive we re-inserted it and tried the same process, and again we noticed some peaks and slowdowns with our test PC system.

Even with writing cache enabled, writing performance drops were visible from 800MB/sec down to 50MB/sec.