How to Fix Slow Speeds of Samsung TLC SSDs in Ultrabooks

Kannon Yamada 10-09-2015

Many Windows Ultrabook Solid State Drives (what’s an SSD? How Do Solid-State Drives Work? In this article, you'll learn exactly what SSDs are, how SSDs actually work and operate, why SSDs are so useful, and the one major downside to SSDs. Read More ) suffer from a crushing flaw. After approximately 9-40 weeks, their Samsung drive’s read speeds How Ultrabook Performance Degrades Over Time with a Samsung TLC SSD Samsung's TLC SSDs are screwing their customers! A bug with Triple Level Cell NAND memory causes performance to degrade and voids warranty early. Find out whether you're affected and get a fix. Read More grind to a crawl, thanks to their Triple Layer Cell (TLC) memory modules. The problem also afflicts anyone with a Samsung 840 or 840 EVO SSD (or most drives using TLC).


Fortunately, a fix exists which restores much of the drive’s original performance.

What’s the Problem with TLC?

For me, the problem surfaced when I experienced poor performance on my Dell XPS 13, 2015 Dell XPS 13 2015 Review and Giveaway The XPS represents the pinnacle of laptop design in 2015, and it's the best bang for your buck out of any laptop we've ever seen in the $800 price range. Read More edition. A quick search led to a thread on, containing mention of a temporary fix. At first, uninstalling programs would cause a crash or take much longer than normal. As the problem worsened, the performance of older programs deteriorated.


According to PCPers, it appears that TLC SSD read speeds attenuate over time. Not all files suffer from the slow reads. Strange enough, if a file exists for less than 9 weeks, its read speed won’t deteriorate. But the older a file, the slower it gets.

How Did Samsung & the OEM Respond?

In response, Samsung updated the firmware for the Samsung 840 EVO, but not for any other drive affected by the bug. Worst of all, according to one of Samsung’s customer service representatives, no fix will arrive for any Original Equipment Manufacturer (OEM) drives, as these fall outside of warranty.


I contacted Samsung, regarding the issue. They had published, and then retracted, a fix for the issue on PM851 drives in 2014. I asked Samsung why they removed the fix for the problem, but left the instruction manual online. Their response, although prompt, failed to answer the question:

This is a OEM SSD not supported by us, does not have a warranty with us, and does not work with out software.

samsung responds

In other words, don’t count on them to fix the problem. Considering that a tremendous number of Windows Ultrabooks use Samsung TLC drives, that leaves a lot of us out in the cold.

I also called the laptop manufacturer, Dell. Dell offered more courteous help, but they claimed ignorance of the drive’s defect, despite the problem getting mentioned on their own support forums.


What Other Options Do Affected Users Have?

Without help from either Samsung or laptop manufacturers, what can we do?

Fortunately, thanks to the work of Puran Software, there’s a program called DiskFresh. DiskFresh appears to restore some of a TLC SSD’s performance, although it incurs additional disk writes, which may shorten an SSD’s life expectancy.

DiskFresh works by rewriting some of the data on the drive. This refreshes the files, although it will write an equal amount of data to your hard drive. To illustrate, if you have 32GB of data written to the drive, the program will write an additional 32GBs. This obviously is not a program you want running constantly in the background. Rather, you should configure the software to run every three to four months.

Installing DiskFresh

To install DiskFresh, just download the installer and run it. I’ve scanned the executable using several anti-virus scans (ClamWin, VirusTotal, and Norton Safe Web) and it came up mostly clean.


VirusTotal indicated that one of the companies, Blueliv, associated with Puran Software serves malware. However Puran Software registers green on Web of Trust (which is a must have Chrome extension Web of Trust Data Breach: Accident or Money-Grab? The Web of Trust browser extension has been silently and forcibly removed by Mozilla Firefox and Google Chrome. Did the popular privacy and security extension collecting and sell your data to third-parties? Read More ). However, Google recently classified (and then promptly declassified) the site as a potential malware source, meaning its software might contain malicious code.

In this case, I’m certain the detection was a false positive. Both Blueliv and Puran Software don’t offer malware of any kind. We’ve even reviewed some of Puran’s other programs, such as Splitter, which can break a file into smaller parts.

puran software malware

Using DiskFresh

After installation, run the program. DiskFresh offers several modes of operation: First, there’s refresh individual partitions. Refreshing a partition won’t write over free space, which will limit the amount of writers to your drive. Second, you can elect to refresh the entire “RAW” drive, which will write an amount of data equal to your hard drive size. For example, if you possess a 128GB SSD, choosing RAW mode will write 128GB of data to the drive.


I recommend choosing the option to refresh individual partitions. If it doesn’t work, you can try using the option to refresh the entire drive.

Testing Disk Read Speeds

An application, hosted over at, called SSD Read Speed Tester (no longer available) tests for the TLC slow read bug. You can interpret the data by looking at the clustering of file read speeds and comparing these to the file’s age. The tool also generates a graphical depiction of your drive’s performance, relative to its age.

The chart generated by SSD Read Speed Tester displays disk read speeds on a two axis graph. The X-axis displays the age of each file. The Y-axis displays the read speeds. If you notice an unnatural number of files older than 9 weeks with slower than normal read speeds, then you suffer from the bug. If these slow speeds persist after running DiskFresh, you may have either improperly run the program or your disk issues originate from another cause.

results for c ssd speed tester

If DiskFresh works, you’ll notice that your average disk read speeds will improve. Pay close attention to average data read speed, which displays at the bottom right side of the results page for DiskFresh. For example, here is the result of one of the earlier benchmarks, before running DiskFresh:

SSD speed before

As you can see, the average disk read speeds fell short of the advertised maximum reads of the PM851 drive. A lot less. Most SSDs saturate the sequential read capabilities of the SATA 3 channel.

Here’s the results after running DiskFresh:

SSD speed after

The average disk read speed skyrocketed from 158 MB/s to 392 MB/s.

Say Goodbye to TLC Memory

So, more or less, your TLC drive will lose a lot of its speed over the course of its lifetime. Refreshing Windows 8.1 How To Restore, Refresh, or Reset Your Windows 8 Installation In addition to the standard System Restore feature, Windows 8 has features for "refreshing" and "resetting" your PC. Think of these as ways of quickly re-installing Windows -- either keeping your personal files or deleting... Read More or 10 also restores performance, but it forces users to reinstall their software. Samsung’s V-NAND appears to not suffer from TLC’s issues, but it hasn’t been on the market for very long and might suffer from a similar issue.

At the beginning of 2014, TLC drives came from only one source: Samsung. Since then, recent technological innovation from IM Flash Technologies (IMFT) led to XPoint memory Intel Storage Breakthrough Enables Instant Bootup What if you never had to look at a loading screen again? What if computers booted -- not "in seconds" -- but instantly? Recently, Intel announced a new technology that could make all this possible...and... Read More , which represents a quantum leap in SSD technology.

Intel intends on releasing the XPoint in 2016. If it does, flash memory prices should begin a relentless tumble into oblivion. Anyone seeking to upgrade their hard drive should consider waiting a year and seeing what ripples XPoint makes in the industry.

Given the upcoming technology, TLC seems like a technological dead-end.

Have you encountered this issue and was DiskFresh able to fix it? Are you considering to upgrade your SSD to enhance performance?

Related topics: Computer Memory, Solid State Drive, Ultrabook.

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  1. Hrobky
    March 24, 2020 at 2:00 am

    Thank you. Worked with my prehistoric Samsung non-EVO SSD. Used to freeze computer for seconds during startup. Now is the reading "speed" restored to 167 MB/s.

    • Kannon Yamada
      March 24, 2020 at 6:40 pm

      Thanks for letting me know!

      Samsung eventually issued a firmware update for its EVO line that periodically refreshes cells in the background. It was never sent out to their OEM partners (such as Dell, etc...) so many laptops will not receive this update. Also it has to be run every few months as performance will continue to degrade over time.

      On top of that, I've seen abnormal failure rates from TLC-based drives from that time period. It may be because on the modified firmwares, there are now additional writes being done to keep the drive's performance up.

  2. PaulR
    October 5, 2017 at 9:32 pm

    Could someone upload & post a link to the fix that Samsung published in 2014, and then retracted? The files were Samsung_PM851_Performance_Restoration_v10_Installation_Guide.pdf and

  3. aaa
    May 3, 2016 at 9:18 pm

    The funny thing is that Dell still did not update the firmware to latest version. Samsung released two firmware updates in 2015 for 840EVO.

    Dell picked up only first one for PM851 OEM version of 840EVO SSD drive used in Dell equipment.

    Second firmware is actually actively refreshing disk, so slowness should be hidden issue but at least no need for DiskFresh (DiskFresh worked for me only for 2 weeks, after that ssd is slow again).

    Now we have 2016, yet Dell is not doing anything to help its users.

    Point is - never trust Dell and never buy their laptops in future :-(

  4. Anonymous
    September 10, 2015 at 9:19 pm