Samsung 840 EVO SSD Read Performance Degradation #1

Sadly enough, the old data read issue has been present on the Samsung 840 EVO series solid state drives since their initial release in 2013. The bug appears in the form of constant old data read performance degradation over time, meaning, the older the files on the 840 EVO drive get, the slower the drive will read them. However, if the old drive content is freshly rewritten, the read performance will be at its peak for some time before it starts to decay again.  Samsung was well aware of this issue and its attempt at fixing it was the release of the EXT0CB6Q firmware, however, most users are reporting the aforementioned problem is still ailing the 840 EVO series solid state drives.


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 I have been running two Samsung 840 EVO 120GB drives in RAID0 configuration for a few moths now, long enough to be able to share my read performance results with you.

Test setup: ASUS P6T Deluxe / Intel Xeon X5670 / 12GB 1600MHz RAM / 2x120GB Samsung EVOs. Please note I am running quite an old motherboard lacking the SATA3 support, which means I am limited to only SATA2 speed. Ideally, I should expect the read speed of up to ~600MB/s            (300MB/s x 2 because of RAID0).

Before I begin testing the performance of my RAID0 array, here is the screenshot ensuring both drives are healthy as well as on the latest firmware, the EXT0CB6Q (pic. 2).


Picture 2.


Back in December of 2014, I ran the DiskFresh utility to fully restore the drives read performance and I have been monitoring it since. The array has 160GB of free storage space. Let’s take a look at the read performance in HD Tune, shall we?

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Picture 3. HD Tune

As seen in picture 3, the integrated SATA2 controller is capable of sustaining the read speed  of 540MB/s on average in RAID0. Maximum and minimum speeds are pretty close to the reported average, which is good news. One month later (31st , Jan.) things start to look a bit worse. Although the average and maximum speeds did not change much, the minimum read speed is another story here as it went down from the respectable 494MB/s to 382MB/s in just a moth’s time. If you pay heed to the speed graph, the second run looks much less consistent compared to the first one. The last, third run is the reason I decided to compile this post on my blog. You can see the average and minimum read speeds went down even further and hit  the record low of 410 and 115 MB/s respectively. Not to mention, the graph has become extremely inconsistent and shameful to look at in just two months’ time.

Speaking from a real-world performance standpoint, all I have noticed is Windows 7 now takes about 14 seconds to boot in comparison to 10-11 seconds it would take in December, 2014. Although ~3 seconds does not seem like a long period of time, it actually accounts for a whopping ~30% of increase! That being said, I am still reluctant to run the DiskFresh utility every two months or so, as frequent SSD content rewrites do take a bad toll on the TLC-based drive’s longevity.

The good thing is Samsung has reported to be working on a new firmware update addressing the issue, which, hopefully, turns out fine this time.

Update 2nd April, 2015

It has been another month without a firmware update addressing the old data read speed degradation issue and it looks like the speed has gone down big time. Twice to be exact.


Creating a Bootable USB Drive and Booting From It

Since USB drives are relatively cheap, capacious and readily available , they have been successfully replacing the old-school CD/DVD media for quite some time now. Although the latter is still a good option for movies or music long term storage,  it is not worth the hassle elsewhere as it introduces more variables to the game like third-party CD/DVD burning software and takes forever to write.  That is the main reason you may consider using a USB drive instead. In the following steps I will take you through the steps of creating a bootable USB drive depending on your needs.

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 Article Contents

Creating bootable USB drive for Windows 7 / Windows 8 / Windows 8.1
Creating bootable USB drive for Windows XP
Creating bootable USB drive for  drivers or a BIOS update
Setting up BIOS to boot from USB drive
Creating Bootable USB Drive for Windows 7 / Windows 8 / Windows 8.1

Step 1. Download, extract and install the Windows 7 USB DVD Download Tool. Don’t worry, it works with all three operating systems just fine.

Step 2. Open the tool and click “Browse” to select the ISO file containing your Windows 7 / Windows 8 / Windows 8.1 operating system (pic. 1). Once selected, click  “Open” and then “Next”.

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Step 3. Click on “USB device” (pic. 2).


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Step 4. If you have more that one USB device connected at the time of following this guide, make sure you choose the one you are planning on putting the operating system on in the drop down menu and click “Begin copying” (pic. 3).

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All you have to now it to wait for copying to complete and then you are done.

Creating Bootable USB Drive for Windows XP

Step 1. Download, extract and run Rufus tool.

Step 2. In the drop down list choose your USB device you want to copy Windows XP to. Next, click the button with a disc picture on it (marked in red, pic. 4), select the Windows XP ISO file and click “Open”. You do not need to change any other settings here. Click “Start” to begin copying files.

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Picture 4

Be patient and wait for copying to complete. Now you have a bootable Windows XP USB drive ready to boot from.

Creating Bootable USB Drive for Drivers or a BIOS Update

Step 1. Download HP USB Disk Storage Format Tool and boot files. Extract both archives and launch the tool. If the tool gives you an error on launch, make sure you right-click on it and select to run it as administrator (pic. 5).


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Step 2.  Select your USB drive in the top drop down menu. The file system should be set to FAT32. Next, check the “Quick Format” and “Create a DOS startup disk” boxes and then select the location of the boot files you have extracted (pic. 6).

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Step 3. Click “Start” and confirm you want to format your USB drive in the pop-up window (pic. 7).

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That is all. You can now put a BIOS file, drivers and an  updater utility on your USB drive and boot from it.

Setting Up BIOS to Boot From USB Drive

When you turn on your computer, the BIOS first initializes all the components connected to a motherboard. Next, it checks for a bootable drive and this is the moment when boot device sequence really matters. If there is more than one bootable drive, say, a hard disk you have your OS on and a USB bootable drive you have just created, the BIOS will boot from a device which comes with a higher priority. So if you cannot boot from a USB device, it is likely your boot device priority is not in correct order and needs to be changed. Long story short, you should give your boot USB  device the top priority  in BIOS.  In order to achieve it, you have to:

*In the following steps ASUS BIOS will be used as a reference.

Step 1. Plug your newly created bootable USB drive, restart your computer and before it begins to load the operating system, depending on your BIOS, press “Esc”, “F1″, “F2″ or “Del”. Usually the BIOS logo screen shows which key should be pressed in order to enter  the BIOS configuration utility. For example, all ASUS motherboards enter the BIOS configuration mode when “Del” is pressed during a boot up.

Step 2. Once in BIOS, locate the Boot menu (pic. 8). If your non-Asus motherboard has a different BIOS layout, the boot menu should appear under “Advanced BIOS Features” or similar section.

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Step 3. Now, head over to “Hard Disk Drives” section where you will be able to see all HDD, SSD and USB drives currently present on your computer. By pressing “+” key make sure a device named “USB: Generic Flash” is the 1st drive on the list (pic. 9)


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Step 4. Press “Esc” to return to the main boot menu. Now go to “Boot Device Priority” section and do the same thing as you did in step 3 and make the “USB: Generic Flash” appear on top of the list again (pic. 10).

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Step 5. Confirm the changes you have just made by pressing “F10″. Finally, click “Esc” to leave the BIOS setup utility.  Now you should see your computer booting from a USB drive.

A Shorter Way of Achieving the Goal

Rather than going through all the steps mentioned above, you may just try to bring  the advanced boot menu by repeatedly tapping (not pressing and keeping pressed) “F8″ key as soon as you power on or reboot your computer. You should see a window similar to the one in the pic. 11. Select the “USB: Generic Flash”, press “Enter” and watch your system boot from a USB drive. The reason I offer this seemingly better solution as secondary is that not all BIOS versions support this feature. Another thing is this feature does not save the boot device priority list, so if you need to boot from a USB drive more than once, you’ll have to be vigilant not to miss to tap “F8″ everytime.

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Picture 11