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I have created 2 new volumes on the SSD (Samsung 840 Pro 256GB) from the previous OS installation before re-installing Windows 8 Pro 64 bit on it.

After installation of: Windows, all the latest drivers from the official Acer site for the laptop (Aspire V3 - 771G), doing a Samsung SSD Magician performance optimization and OS optimization and removing the page file I get these results when running AS SSD Benchmark:

and the benchmark in magician:

which are very low (about half) compared to the results it should return.

I found on Google 2 benchmarks, both having much better performance (closer to expected as in the product specifications):

Things I have checked/tried/are known:

  • connected to a SATA3 port
  • AHCI is enabled in BIOS
  • TRIM is enabled
  • Partition Starting Offset is aligned to a multiple of 4096 for both SSD partitions
  • configured and switched to high performance windows power profile

Any ideas what it could be? Or how to diagnose?

Thanks for your help!


I found the problem by looking in Intel Rapid Storage Technology program - the mode used by the SSD is SATA 2:

Any ideas on how to make it work in SATA 3 mode instead of SATA 2?

I am thinking that it might have something to do with the HDD which cannot work at more than SATA2. Maybe, even though the 2 SATA ports are SATA 3 compatible, the main one in which the HDD is connected is faster, or maybe the HDD is limiting the SDD speed cause it has to use SATA2.

share|improve this question
Have you checked the S.M.A.R.T. data to check the wear? Have you performed a secure erase on the drive? Have you updated to the latest firmware? – Stefan Seidel Feb 7 '13 at 14:38
@StefanSeidel: yes, I done a firmware update immediately after installing magician, I have not done a secure erase and the SMART data showed OK on all rows – Răzvan Panda Feb 7 '13 at 14:53
Just OK doesn't mean great. Can you see the total GB written in the SMART data? I mentioned secure erase because that's the one operation that guarantees maximum performance (if benchmarked right after it). – Stefan Seidel Feb 7 '13 at 14:56
@StefanSeidel: this is the data I get from SMART: – Răzvan Panda Feb 7 '13 at 15:01
@StefanSeidel: better layout – Răzvan Panda Feb 7 '13 at 15:08

Write caching may not be properly enabled and worth going through a few steps to check.

Go to Device Manager

Right-click on your drive then select Properties

Click on the Policies tab.

If Enable write caching on the device is already ticked then un-check it then click ok.

Now retick the box and click ok.

Run your benchmarks again.

share|improve this answer
I am getting about the same results after disabling and re-enabling write caching – Răzvan Panda Feb 7 '13 at 16:55
@RăzvanPanda - are you sure you have ahci enabled? it looks like on your benchmark test vs the Fast test sample you provided that iaStorA is - OK, while the Fast sample shows msahci - ok. If this is the issue, I will update my answer. – Carl B Feb 7 '13 at 20:47
Yeah, very sure, AHCI is enabled. iaStorA afauk is an AHCIdriver from intel. I am considering swapping the normal hdd with the sdd ports and doing a secure erase. – Răzvan Panda Feb 7 '13 at 21:44
It seems that the SDD runs in SATA2 mode (question updated). – Răzvan Panda Feb 7 '13 at 21:59

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