Fix a suddenly very slow SATA hard drive problem

So, I was happily copying files around on my Windows Home Server, when I noticed that the speed of the transfers were now at 1.5MB/s… Uncool, when copying similar files from the same directories was at 50-80MB/s minutes earlier.

I tried to think what I might have changed since it worked fine. I tried reseting the CMOS, disconnecting all hard drives (IDE, USB, SATA) that were connected, except my primary drive, to no avail. OS was still very slow to load, and when I did let it load, I still measured 1.5MB/s transfer speeds using HDTune

I finally found a solution. Disconnecting the SATA data cable from the first SATA port on the motherboard (where it was always connected), and connecting that same cable into the last SATA port. Bingo! Instantly, I’m back transferring files at decent speeds. I don’t know the exact cause of the problem, and I didn’t yet try that 1st SATA port with other hard drives, to see if the problem is with the port, or the hard drive & port combination. What’s important is that it now works fine!

I have to thank this guy for the idea on how to fix this.
I guess I would have tried that at some point, but at least now I know I’m not the only one who had this problem. And I’m reposting the solution here, just to insure anyone else who faces this particular problem in the future can find this solution faster than I did!

10 thoughts on “Fix a suddenly very slow SATA hard drive problem

  1. Hi, I’m having the same problem for some years now with my computer, all of a sudden the speed of SATA drive(s) drop to ~1.5 MB/s (measured by HDTune and HDTach) and everything slows down and sometimes system hangs up.
    I ensured HDDs work properly on other Mobos, checked SMART values, everything seemed fine.
    Things that solved problem (temporarily):
    -Reinstalling XP
    -Replacing the SYSTEM registry hive of windows registry (where driver, service and activation settings are stored among other stuff) with the one from C:\Windows\repair
    -Booting in safe mode (not a real solution, doesnt solve problem in “normal mode”)
    -Replacing the mobo with a different one

    Changing the Mobo solved the problem until today (some months since last error).
    First, only the primary HDD was affected, the other one stil ran at full speed.
    Now, both are slow and the problem even occurs in safe mode.
    I really would like to know what is causing my constant problems, which seem to be exactly like yours.
    I’ll do some more investigation, however it can only be one of these:
    1) Faulty hardware (no onboard HW)
    2) Faulty driver for hardware (no onboard HW)
    3) Faulty driver for virtual HW, i.e. CDROM emulation
    I’ll post any results.
    Greetings, mbit

  2. Hello again,
    changing the SATA slot did the trick, thanks.
    Unfortunately not a very satisfying solution, who knows when it happens again?

    greetings, Mbit

  3. I have an XC-cube with 1 TB Samsung SATA drive and can report the same problem. Sudden drop of 30 Mb/s to 3 Mb/s. Putting the HD from first to second port solved the problem. But then the Instant-On function (quick mp3/video/picture/radio/TV ability without starting any OS) is sacrificed.
    After several month again speed has dropped to 3 Mb/s. No more SATA ports, no lasting solution!! I use USB drives now to keep performance.

  4. THERE IS A LASTING* SOLUTION AFTER ALL!! You will find it here: http://winhlp.com/node/10.
    To put this extensive article simple:
    1) click “Start”, “Run…”; type “regedit”; click “OK”
    2) browse to “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}”
    3) click on the “0001″ subkey in the tree directly under it
    4) delete the entries “MasterIdDataCheckSum” and “SlaveIdDataCheckSum”
    5) click on the “0002″ subkey in the tree directly under “0001″
    4) delete the entries “MasterIdDataCheckSum” and “SlaveIdDataCheckSum”
    NOTE: not all of these entries need be present, just delete the ones that are
    5) reboot

    The drives should perform back at full speed again.
    Look at the site above for all explanatory details. In short: data transfer has been permanently set to (slow) PIO, above method forces it back to (speedy) Ultra DMA.
    *Be aware that PIO has been set with a reason (bad HD, scratchy CD/DVD), so it might happen again.

    (Above info originally by Alexander Grigoriev & Hans-Georg Michna)

  5. hm cant find “MasterIdDataCheckSum” and “SlaveIdDataCheckSum” when i even search for them in the registry, theyre not under 0001 and 0002 either hmm but harddisk transfer mayber 5,6,7 mb a sec,then take a pause for some secs, then back to 3,4,5, then back to pause, it make system hang hmm

    1. same here .. help . it may be something to repaire at hd or change it .. i get this thing when i open pc = no hd found .i check cable who was a wery litle off place reopen pc and work but wery slow and hang also .

  6. I have a SATA drive that has suddenly started operating at only a few hundred kbps, but it is looking like the drive is at fault. Changing SATA sockets did nothing for me. Bummer.

    I just stopped by to let those of you trying the registry tweak know that the MasterIdDataCheckSum and SlaveIdDataCheckSum entries describe drives operating in IDE mode. Emulating IDE results in a noticeably slower data transfer rate than native SATA, but the drop to PIO data rates (even slower still) may be caused by the same error. I am starting to suspect that this issue for the majority is rooted in impending HDD failure, for instance, and/or a controller issue (with each SATA channel ‘burning out’ in a degenerative sequence). Bad chipset?

    Now, of course, I am faced with the prospect of attempting to back up 1TB of data at no more than 1Mbps. Thankfully, it’s a secondary drive used for media storage (mostly replaceable).

    1. I have also been suffering from the same problems, but on a laptop. Famings solution worked for me also, but I had to look into the higher numbers folders (0003,0004, …, 0008). However, I *do* know that my hard drive it dying as it is starting to show bad sectors (use a tool to look at the hard drive SMART info).
      You can confirm Faming’s problem cause and fix by looking in the Device Manager. Right click on the Primary IDE controllers and on the second tab you will see the info about what mode the attached drive is operating in (PIO or Ultra DMA).

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