13 Replies Latest reply on Dec 23, 2012 1:05 PM by Boyet

    USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8


      I had been testing my 3.0 transfer speeds when I decided to try the Smart Response Technology using a 32 GB SSD.  After I had enabled Acceleration and things looked normal, I noticed my USB 3.0 transfer speeds had dropped to USB 2.0 transfer speeds.  Namely, copying a file, to an external 3.0 device changed a 125 MB/s speed to 14 MB/s.  Even disabling Acceleration would only allow the speed to go to 75 MB/s and never returned to the original 125 MB/s.  Speeds would only drop off from the initial speed after the first 5 or 6 GB of data transfer, or first few seconds.


      It should be noted, that during my testing, a transfer between 2 external USB 3.0 devices remained at 125 MB/s and stayed constant during the entire  transfer of both a 12 GB and 16 GB file/s.  So the title of the thread may be misleading, but it should fulfill my intent.



      Motherboard ASUS P8Z77-v Pro

      Processor:  i7 3770K

      Memory: 16 GB


      I noticed the problem on my normal Windows 8 system.  So I decided to do a fresh install and load the drivers in stages.  The first test was with no extra drivers, The Second was with the Intel Rapid Storage Technology driver for Windows 8 from ASUS. And the third was with Acceleration enabled using the 32 GB SSD.   I will try an Intel driver for a Z77 motherboard later, but have not yet done so.


      The first two tests showed a good speed for the USB 3.0 to internal file transfer.  The speeds were a little better and more stable with the Intel driver installed.


      After Acceleration was enabled, a transfer that would run a 230 MB/s for the first few seconds and then drop to 125 MB/s, now started at 125 MB/s and dropped to 14 MB/s.  Same file and same transfer process.


      I also noted Internal transfers to same the hard drive, on different partitions, or internal hard drives on different controllers also showed speed problems. 


      So my conclusion is the Intel SRT severely limits transfer speeds between external USB 3.0 to internal, or internal to internal drives.  The title was chosen to alert folks thinking they have USB 3.0 driver problems, may actually have something else.  I know many of the HP computers have mSATA drives which may be involved with this same process.


      If anyone can recommend testing in a different manner, please advise.

        • 1. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

          Did you have an appreciable speed increase of your mechanical hdd due to the activation of SRT? I understand that the ssd in this case is acting as a cache.

          • 2. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

            The only thing I am testing is the file transfer rate, since that is where I noticed the problem.


            As far as checking the prefetch type capability of the SSD, not sure even what would need to be checked.  But for the short time the SSD has been set up, I have not noticed anything.

            • 3. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

              AFAIK SRT will increase the speed of the mechanical HDD where the OS is installed and the SSD used only as the cache. I don't have SRT feature in my mb, that is why I'm asking for a possible upgrade later on. Test can be done using utilities (Anvil's Storage utilities for example) to check the mechanical hdd speed first (not the SSD) then the usb ports with devices attached to check USB 3.0 & 2.0 speeds.

              • 4. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                I suppose, Boyet, the specifics of the SRT are not relevant if the system performance during transfers drops 90%.  So I won't be doing any testing on the SRT itself.


                But I have done more testing, while moving the focus to the overall transfer rates of the system.  I have noticed, by using 2 Windows 7 systems and 2 Windows 8 systems, that while the Windows 7 transfer speeds may only drop 10% during a large file transfer, the Windows 8 will drop 30-40%.


                Also, adding the SSD, to use as a cache, does not seem to effect Windows 7 but causes Windows 8 transfer rates to drop 90%, or an additional 50% from the normal decrease.


                I do not know what Windows 8 is doing, but it appears it needs to be addressed...

                • 5. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                  Although I don't have SRT I do use IRST. Test using utilities showed that there is a great increase in the raid hdd speed. However, doing an actual file transfer using USB 3.0 showed a drop of actual speed from 40 or more mbps from a previous configuration which does not use IRST. I used to get using USB 3 ports from 40 to 170 mbps file transfer speed but now with IRST installed I only get utmost 80 mbps.


                  It seems the problem is with IRST which is also use in conjunction with SRT in your case. BTW I'm using Windows 7 64bit.

                  • 6. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                    I am continuing my testing, and converted a Z68 board with Windows 8 to RAID and set up the Acceleration again.  The same results were obtained, namely large drops in performance when transferring files, even internally.  I have only used one SSD for my testing, and since it is new, hopefully there isn't something wrong with it.


                    But the picture below illustrates part of the problem.  Today I noticed if I started Disk Management, or Diskpart during a file transfer, the speeds would return to the original speeds for a short time.  It took both Disk Management and Diskpart around 30 seconds to start after I actually started them.



                    • 7. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                      I confirm your observation regarding the drop in file transfer speed when Disk Management is initiated. But its only for a few seconds. This must be normal since Disk Management is accessing the available drives of the system. Even when transferring several files you can see a variation in speed without initiating Disk Management. For a longer and stable level of speed you can try transferring a single but very large file size.

                      • 8. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                        The transfer speed does not decrease with Disk Management, it increases.


                        I am attaching 3 pictures.  The first is a transfer with Acceleration disabled.  The other two, with Acceleration Enabled, are of the same transfer at different periods.  Both transfers used the same file and were copied from and to the same locations.


                        I have no idea why the speed increased at the end.  It might also be noted, when I opened a browser during the transfer, the speed dropped even more.  Probably because the OS drive is already running at 100%.





                        • 9. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                          Here is what I have observed: Please refer to the picture below. When I click the "Disk Management", at first, there was no decrease/increase in the transfer speed. The Disk Management windows appeared but the right pane is still blank. After sometime there is a dip in the transfer speed then the speed starts to go up. At the Disk Management window at this time, all Disks info then appear.

                          Disk Management effect.JPG

                          • 10. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                            What you are showing, Boyet, would seem to be a normal situation.  My illustration goes the opposite direction... What ever is slowing down my transfers when my system is Accelerated is temporarily negated somehow by both Disk Management, and Diskpart....  I was hoping someone from Intel would take notice and realize what was going on.


                            You do not have your system accelerated using SRT, correct?


                            I wish mine would look like the following all the time.



                            • 11. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                              As stated earlier, my mb does not have the SRT feature. What I'm trying to say is that whether the mb has SRT or not the common factor in both case is the use of IRST which I have observe in my case affected the transfer speed in particular through USB 3 ports.

                              • 12. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                                It looks like I found my problem.  When I tried the Acceleration on a Windows 7 machine with a second generation processor and it did the same problem, I decided to replace the SSD.  Now my transfer rates stay at the initial, high rate during the entire process.


                                The SanDisk SATA III drive I was using shows a 450 MB/s sequential read speed, but a 115 MB/s sequential write speed.  I got an Intel 520 SSD with 500/450 read and write speeds and that drive appears to be working fine.


                                I will expect my USB 3.0 speeds to also show the same result as the internal transfer speeds.  The actual speeds you may see depend quite a bit on the drives involved.  My two SATA II drives seem to have a top speed of 125 MB/s, which is about whet Western Digital shows.  I was very excited to see the 409 MB/s speed when using two internal SATA III SSD drives.....


                                Thanks for your help Boyet.  If there is something you want me to check for you, let me know.

                                • 13. Re: USB 3.0 to USB 2.0 speeds with Intel SRT Windows 8

                                  Glad to hear that you have it all sorted out. I cant disagree more or less that the kind of SDD is also a factor that one has to consider. Yes I have seen that value a while ago when I have the Release Preview installed but I can't  achieve it with the final copy of the snappy Win 8. For the mean time, I'll try to explore why this is so. At least the acceleration feature is one option to look for and consider for an upgrade in the near future.