Helpful info to perhaps alleviate VIA's 686b bug?

Okay, I was just messing around, looking up helpful articles. I stumbled across <A HREF="" target="_new">this one</A>. But, the important one I read was #44 (You'll know what I mean...)

Here it is if you don't want to click that link. It wasn't me, so I'm not to be given credit:

44. Posted by Dr. John
at 09:56 pm
on May 11th 2001
x It has been our contention for some time, based on our experience building Athlon computers that have to work right, that the VIA bug is real, and they have basically adimitted the fact, with the stipulation that Creative was a contributing factor. This is the standard take on the problem as picked up off of one of VIA's boards:
VIA has confirmed a data-damaging glitch in its 686B southbridge chip - a major part of the Taiwanese company's KX133 and KT133A chipsets - and is working with mobo makers to prepare BIOS updates to fix the problem.

The bug was uncovered by German hardware site Au-Ja! It's not exactly a common problem: the data corruption affects large, 100MB and up file transfers between two ATA-100 hard drives exchanging the data by DMA. Having a Creative Labs Soundblaster Live card in place seems to exacerbate the problem.

VIA's BIOS fix works by adjusting a number of PCI settings, which, according to TechChannel, suggests the problem is a result of competitive PCI access.

Set PCI Delay Transaction to off
Set PCI Master Read Caching to off
Ensure the PCI Latency <= 32

If your BIOS supports it, you can change the options there, otherwise there are some VIA tools that can set the registers on the 686B to achieve the same effect.

Presumably the VIA patch that's to be released will do all this automatically.

The original English article is here:

These guys explain it in plain terms fairly well.

From my readings, I remember VIA as the one who said that the problem occurred when there was "excessive traffic on the PCI bus". I think there may be two issues here, and you all may be able to clarify the situation. The first is DMA access. We found a long time back that disabling the "DOS SB 16 emulation" for the Live series reduced the problems, but often did not eliminate them completely. The SB16 emulation feature takes up two DMA channels, along with an IRQ. The SB Live also seems to exhibit occasional problems when certain CD/DVD/CDRW drives have DMA access enabled. Something seems wrong with the way the SB Live emulation crap uses DMA channels.

The next issue is the 686B southbridge/PCI bus issue itself. I'm not sure how the two interact, but they do, and end up creating a much bigger problem than you'd see otherwise. So yes, the bug is there, it has to do with DMA-enabled drive access, and anything that exacerbates the traffic collisions in the southbridge and associated bus makes the problem much worse. Creative and VIA were both sloppy, and together thay can crash and burn.


VIA makes cheaper products on a comparatively shoe-string budget (although that's changing). Our busines has been able to stay afloat on AMD/VIA sales.... we would have died if we had tried to pull a Dell-like Intel-only thing. VIA gets a very positive rating from us because they got to "near-Intel-quality" pretty quickly, and they are helping kick Intel in it's lazy butt. We can sell fast, reliable Athlon systems very inexpensively because of these two, much smaller companies, and that wouldn't be true if we were trying to sell P4 systems.

Note that when we set up Athlon systems (KT7A-RAID, A7V133) we follow these critical rules:

Keep each IDE device on their own controller. Put the hard drives on the RAID controllers (Highpoint or Promise), and put the CD/DVD/CDRW drives on the ATA/100 controllers. Do this, and disable SB16 emulation, and you won't have any problems (at least we don't). This limits you to 4 IDE devices.

U160 SCSI drives would also obviate these problems (my favorite solution).

I wish VIA would grow up and publish everything, from all technical specs to all known errata, but they are a Taiwanese company, so don't expect them to act like a big US company any time soon.

Over time, VIA chipsets will get even better.

Perhaps we can try changing these settings in our BIOS. But, I don't know how to test them out. If someone can know how to do so...ya know... Those settings mentioned in that post are in the BIOS for the A7V133, though. That's the motherboard I have. My hard drive is in the ATA100 slot, though, so I'm not sure if it affects me.

Anyways, can we all just figure out what to do until VIA comes out with a frickin fix? (Don't bugs me too that we, the consumer, have to figure out fixes instead of the company. :mad: )

<i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
11 answers Last reply
More about helpful info alleviate 686b
  1. Okay, I've just tried some stuff out:

    I set the BIOS to it's defaults, then changed all the settings I knew needed to be changed. It turns out that those settings mentioned in the article/post were already set by default. (I'm using BIOS version 1004) My hard drive is plugged into the Primary IDE, while my CD-RW is in the Secondary IDE.

    I have yet to try disabling SB16 emulation (BTW, I have no clue what it does). Do I just go about it by disabling it in the hardware profile under device manager?

    (Man...I hope someone looks at this thread... :frown: )

    <i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
  2. I read an update on the 686chipset here;

    An excerpt says;

    Regarding the "VIA 686B data corruption" issue. The issue should be the description as following , In fact , it is a specific problem . It only occurs on " K7 series north-bridge with 686B " on a specific Creative SoundBlaster Live PCI Sound card . Only when executing copy compare with a big file (more than 100 MB) , the system would hang ,not corruption . This should be a compatible issue. VIA will release a patch driver to fix the issue soon .

    So let’s take a look at what is being said here…

    It’s only a K7 Series Northbridge & 686B issue when using a SBL and large files. So that means to me VIA feels it could be an issue with either a VIA KT133 or AMD 760 Northbridge if using the 686B Southbridge, but not with a Socket 370 Northbridge.
    Only large (100MB or more in size) files when copying.
    It’s not a matter of data errors but system errors (hang, lock-up, blue screen,…).
    VIA will release a patch soon to solve the problem

    And later;

    Issue #4 – Although I have not received any patch officially, nor have I seen it on an official VIA site, there is a version that appears to be a complete usable patch at (no connection with VIA, it is an independent site). The patch is called ‘VIA PFD’ and is dated just over a week ago (5/4/2001). So VIA is working on it (be patient, it takes time to not only find exactly what the issue is but also find a solution and test it).

    So there you go...
    Via is naturally working on this problem. I'll betcha Creative and AMD are in close contact with them too. It's all part of business. Push it out the door..we'll patch it later. It seems to be the way everything is today. Greed and the bottom line. And all of us that live on the "bleeding edge" of technology are the ones that help squash the bugs.

  3. Have you checked the links I've given? They are updated as of today, not as of 5/4/01.

    BTW, do you have one of the affected motherboards?

    <i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
  4. Can we clarify the problem this is talking about? I hear a lot about the SB live (etc...) problem, but I wonder if this is all part of the same. I have the Asus A7v133, and I've tried 2 different sound cards (turtle beach montego & Sonic Impact A3d - Both old A3D cards). They use PCI-bus mastering, and every so often when playing music (winamp/media player) and doing other stuff like File Manager, etc... my computer freezes. I read about cards sharing the same IRQ's, and a problem with PCI-bus mastering incompatibilities. I know that on my computer my video card, ny network card, and my sound card all share IRQ 9 (I can not manually or automatically get those cards on different IRQ's for the life of me), and I do know that my sound cards use PCI-bus mastering. So my question is, is this the same error as described above that is common with a lot of people's VIA's, and is "supposedly" getting a patch?
    (btw, using windows 2000)
  5. The SB Live is mentioned because it worsens the problem (if you have any). Since you don't, that's one less thing to worry about. I'm not sure what you do for Windows 2000, but just install the VIA 4-in-1 drivers v4.31, and in the BIOS, set "Plug and Play OS?" to No. Leave all the settings for the PCI cards to auto.

    BTW, it's okay if they share IRQs...that's supposed to happen. (I really don't want to go long. Only if you ask though.)

    <i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
  6. <A HREF="" target="_new">JohnGattVIA</A> just posted something to try and clarify the problem at hand. I can't tell if he's official, but I think he is lookig at his bio, because he newly registered. Just click that link to view his post in this forum...

    <i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
  7. btvillarin
    The links I gave were from 5-14-01. Go to the link :)
  8. But I don't think that guy that wrote that article (John Howland) didn't see that at <A HREF="" target="_new"></A>, there are newer 4-in-1 drivers (version 4.31). His insights do help though, so it's all good. :smile:

    <i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
  9. btvillarin,

    Yes I do indeed work for VIA Technologies, Inc and officialy represent them in my posts. I can be contacted at

    John Gatt
    VIA Technologies,Inc
  10. I believe you are...

    Can you read this article at <A HREF="" target="_new">RealWorldTech</A> and tell me if the writer was right on anything?

    Thanks for posting. :smile:

    <i>OC...unless your computer's cheezy (is that a good rhyme?)</i> :eek:
  11. RealWorldTech is right about a lot of things.
    It is a very good article.

    John Gatt
    VIA Technologies,Inc
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