My new Samsung EVO 860 write speed varies wildly from test to test.

Sometimes the write speed is over 530 mbs, but mostly stuck at about 330 mbs.

I also have a 3 years old EVO 850 120 GIGS and it writes much faster...

Is this normal? This SSD is under warranty for replacement, I have 24 hours left, does it sound like a lemon to you?

My system is i5-8400 with 16 GIGS of RAM and WIN 10, brand new system.

I also have a brand new Acer Laptop, and it's the same thing, the new SSD writes at about 330 and the old one at about 530...

This has been confirmed with Samsung Magician, Crystal Disk and As SSD.

enter image description here

  • Numbers without units are not useful.
    – sawdust
    Sep 26, 2018 at 18:58

4 Answers 4


According to Samsung marketing, the quoted performance for the EVO 860 is "up to 500" with a disclaimer:

[...] Sequential write performance measurements are based on Intelligent TurboWrite technology [using] CrystalDiskMark v.5.0.2 [...] sequential write performances [outside of the] Intelligent TurboWrite region are 300 MB/s for 250/500 GB and 500 MB/s for 1 TB.

So the performance is as expected.



TurboWrite Technology is a trademark which means "memory buffered". Data is sent to the memory buffer of the drive (the host OS probably has no idea this is happening) and then it is actually written to the main storage at the drive controller's leisure and convenience. The buffer could be "regular memory" (volatile, possible data loss on power loss) built in or more likely it is a faster form of SSD (safer). This buffer will allow the drive to be quicker for the majority of consumer write tasks which are most often a small fraction of the buffer size and rarely sustained long enough to fill the buffer.

TurboWrite Technology creates a high-performance write buffer area within the drive that simulates high-performance SLC. During write operations, data from the host system is first transferred/written to the high-performance buffer at
accelerated speeds and then during the idle periods, the data is moved from the buffer to primary storage region.


Under consecutive write operations with no idle time, the buffer will eventually become full. At this point, the transfer will exit TurboWrite and write data directly to the main storage area of the drive at 3-bit MLC performance.

TurboWrite on the 250GB drive is 520; unbuffered (no TurboWrite) is 270.


  • Why does the new drive get 330 9/10 tests , but the older 120 gets 530+ 100% of the time? I suspect a bad SSD with new one right? Sep 26, 2018 at 16:31
  • I mean it will get 550, and then next test 300...within 1 minute, is that normal? Sep 26, 2018 at 16:34
  • check out the edit
    – Yorik
    Sep 26, 2018 at 16:55
  • 1
    @BrunoVincent Very normal. Every time you do the test, you deplete the drive's supply of erased sectors and depending on how you long you wait (and how TRIM is configured on the OS) you may or may not have enough erased sectors to allow the write test to operate without waiting for more erasing to take place. Erasing is about 100MB/s, so if you have to erase before every write, the results will be quite slow. Sep 27, 2018 at 0:29
  • If it's very normal, why is the 120 gig, consistently nearly twice as fast? I'll return it and post results here later. But according to the tests I've seen online for this model, they all exceed 500 mbps, the 120 GIGS also gets over 500 consistently regardless of trim, cache, system, settings or configuration. Sep 27, 2018 at 3:34

Well, I returned the SSD and got a new one.

Write speeds are now over 500 mbps, consistently.

So conclusively, 300 mbps is NOT normal write speeds for Samsung EVO 860 250 GIGS.

If you experience same issue, warranty is 5 years, return it for a new one and it will solve the issue.


Ok so my brand new 860 Evo 500GB has 370 read and 250 write. There's not errors and trim works fine. I update the latest firmware but nothing change. I change the cable and position in the Sata ports and now I have 550 read and 390 write. Still 390 is quite slow but better than before. Try it before turn back your disk.


I had the exact same problem, but I updated my firmware today, and now it shows roughly the same write speed what samsung advertises in their website. You had stated when you got a new SSD the problem was solved, I believe the problem might have been solved because the new drive might have the new firmware. So what is the solution? just update your samsung magician software, then update the firmware.! Anyway I left this answer here for those who have the same problem.

enter image description here

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .