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Samsung 840 SSD. Low read speeds (write speeds are fine)

Last response: in Storage
July 27, 2013 8:49:14 AM

Hi All

I have recently purchased a Samsung 840 SSD (first time SSD user) and installed it as the primary disk, that holds the OS.

Unfortunately the 'read' figures (sequential and random) are nowhere near to that which is advertised (write figures are fine). Below are the current average readings obtained via Samsung Magician, AS SSD and Atto:

- Sequential read: 360 mb/s (advetised @ 530 mb/s)
- Random read: 6500 IOPS (advertised @ 86,000 iops)

Most features that optimize the performance of the SSD i.e. AHCI, were either activated by Windows automatically or the Samsung software has optimized to offer 'maximum performance. I have also used the Samsung software and CrystalDiskInfo to confirm that the motherboard (Intel HM65 Express Chipset) is SATA 3 and that the SSD IS connected to a SATA 6 gb/s port.

I have now exhausted all avenues and would like suggestions on how this can be corrected. I have seen others suggest that below advertised figures are usually ok, but I feel this is not the case as the write figures seem to be above the advertised figures, yet the 'read' figures are considerably lower.

Many thanks!
July 27, 2013 9:22:35 AM

Using AS SSD, looking at the offset/alignment (main view right below the driver), does it show in green color and with an OK?
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July 27, 2013 10:45:40 AM

lothdk said:
Using AS SSD, looking at the offset/alignment (main view right below the driver), does it show in green color and with an OK?

It reads the following:

Samsung SSD 840
iaStor- OK (in green)
410624 K - OK (in green)

July 27, 2013 10:47:41 AM

I have also followed the link (followed by another link) provided by FKR and everything on the list is enabled/disabled accordingly. I did not have to change anything. Should I assume the batch it has come from is bad?

Best solution

July 28, 2013 3:56:06 AM

Just purchased a Samsung 840 SSD 120 GB capacity, received yesterday, 27th July. I believe this is the same as the OP.

System: Laptop Compaq Presario CQ58-101TU, purchased August 2012, fairly slow laptop. Cost about 250 GBP, so that gives you an idea that it's a pretty budget laptop. I was quite hesitant to buy an SSD as I figured this laptop may not have SATA-3. The manufacturer never once mentions which version of SATA it has in any documentation. Anyways, I went ahead and took a gamble.

I have just put the SSD in the laptop. I ran Magician software and selected Maximum Reliability as my optimisation preference.

Here are the benchmark results. As you can see, Samsung Magician seems to confirm that my laptop does indeed have SATA-3. My results however, particularly for IOPS, are not reaching the advertised speed. I don't profess to understand these numbers, but it does seem more or less in line with advertised speeds - except the IOPS.

Benchmarks I performed are: AS SSD, Atto, HD Tune, Samsung Magician. You can view the album here:

I hope this is of some help. If you are getting significantly worse figures than this, it may be that your system is to blame. Personally, I don't have the faintest idea of how to determine whether it'd be the system or the drive itself.
July 28, 2013 12:34:07 PM

that list is a pretty good list, maybe a chat with samsung rep. you will see the chat jslink on the right side halfway down

the above is only for general chat but maybe you can find out if that is enough for a replacement. then you can just image the drive and do a quick swap.