AMD-K6^®-2, Athlon, or Duron
JPEG Display Problem

PROBLEMS:

• JPEG images are distorted when displayed by Microsoft Internet Explorer V4, V5, or V6
• JPEG images are distorted when embedded within Microsoft Office 97, Office 2000 or Office XP documents
• When the Microsoft Windows Active Desktop is viewed as a Web page, JPEG Images appearing on the Desktop are distorted
• JPEG Images are distorted in ACD Systems applications ACDSee and PicaView
• When MPEG video clips are played, "static" appears within the video, static and pops are heard in the audio
• MP3 audio files and CD-ROM audio is poor, with clicks, hiss, pops, and other distortion
• Adobe PDF files may have missing lines or missing characters and may have missing areas or black blocks when printed
• Some video games that utilize DirectX display random spots and  noise or "hiss" is heard in the audio

Additional Keywords: Win95, Win98, WinME, WinNT, Win2000, Win2K, WinXP, MSIE, MSIE4, MSIE5, MSIE6, MSOffice, Office97, Office2000, OfficeXP, 3DNow!, PMULLW, PMULHW, PMULHUW

SYNOPSIS:

Some AMD-K6^®-2, Athlon, and Duron microprocessors cause JPEG images to be incorrectly displayed in some applications. When you view a Web page containing a Joint Photographic Experts Group (JPEG or .jpg) image file in Microsoft Internet Explorer V4 or V5, the image appears distorted. Although the image size and position is correct, most of the pixels are displayed using incorrect colors. This problem is also seen when you use a JPEG image in an Office 97or Office 2000 document. When the option to view the Microsoft Windows Active Desktop as a Web Page is selected, JPEG images appearing on the Active Desktop are also distorted.

Even on computers that have such an AMD microprocessor with this defect, JPEG image files are correctly displayed using other applications, including Microsoft Internet Explorer V3, Microsoft Photo Editor and Netscape Navigator.

A test, that requires the use Microsoft Internet Explorer V4 or V5, is provided below. A software diagnostic procedure is also given to aid in eliminating other problems that may cause problems that exhibit similar symptoms.

This problem does not affect other image formats like Graphic Interchange Format (GIF) image files.

DISCUSSION:

Some AMD-K6-2, Athlon, and Duron microprocessor chips are slightly flawed. These flawed chips execute most all sequences of computer instructions properly and the vast majority of applications operate properly. However, the algorithm used by a few applications to decode and display JPEG compressed image files does not yield the correct results on these flawed AMD microprocessors. 

It is important to note that this is not a design flaw in the AMD microprocessor product line. 

As a result of uncontrollable factors in the manufacturing process, some percentage of processors on each silicon wafer are flawed. A series of Quality Assurance Tests are run by the manufacturer to identify good chips, and reject imperfect chips. The ratio of good microprocessors to rejected ones is referred to as the manufacturing yield.

Unfortunately, AMD's QA tests used to evaluate all of their K6-2, Athlon, and Duron microprocessors failed to adequately test a small number of instructions. As a result, some chips were released even though they did not execute all instructions correctly in all situations. In 2001 AMD extended its testing suite to detect this problem. Unfortunately, some flawed chips were released during the preceding years.

Only a relatively small number of flawed chips were released. As one would expect, most flawed chips failed another test in the earlier, incomplete, QA suite. As a result, only a relatively small percentage of chips were released that contained this flaw while passing all of the tests in the original QA suite. Nonetheless, several dozen examples of this problem have been reported to this computer scientist. A limited number of PCs using the AMD microprocessors from around the world have been shown to have this problem. 

The algorithm used by Microsoft Internet Explorer V4, V5, or Office 97 or Office 2000 applications, like Word, include a sequence of instructions that does not yield the correct results when executed on such a flawed AMD microprocessor. In these applications, JPEG images are distorted when they are displayed or when they are saved in another file format. In addition, JPEG images that are displayed when you view your Active Desktop as a Web page are also distorted.

MPEG video is also adversely affected when played back. Video games that utilize DirectX display random dots on the screen, and noise or "hiss" is heard in the audio.

Is this problem related to the video card or video driver?

This problem has been observed with both PCI and AGP video cards and a variety of display drivers, including the standard Microsoft VGA driver. The problem is not present in only a very few AMD-K6-2, Athlon, or Duron microprocessor chips. Replacing only the processor chip resolves this problem.

Why are some applications affected, while others are not? Is this a software problem?

Many applications use slightly different algorithms or instruction sequences to decode and display JPEG image files. As a result, those applications will not exhibit the problem even on computers that incorporate such a flawed AMD microprocessor. Netscape Navigator, Microsoft Internet Explorer V3, Micrographx Picture Publisher, and Microsoft Photo Editor are examples of applications that never exhibit this problem. JPEG images will always be correctly displayed by these programs. These programs use a different algorithm that avoids the instructions that do not execute properly on these flawed AMD microprocessors.

One should note that this is not a software bug. The algorithm used by the Microsoft applications is entirely correct. The algorithm used by Microsoft is optimized to take best advantage of some of the special instructions and capabilities of advanced microprocessors. When these instructions fail to execute properly, the observed image and audio distortions are observed.

Other types of images, like Graphics Interchange Format (GIF or .gif) image files are never affected. The decoding and display algorithms used do not take advantage of the associated instructions that are affected by this problem.

Not all AMD-K6-2, Athlon, or Duron microprocessors exhibit this behavior. The great majority of AMD microprocessors operate correctly. On AMD microprocessors that exhibit this problem, the degree of distortion is reduced when the microprocessor clock rate is reduced. In other words, the failing instructions produce incorrect data, and the degree of failure is related to the speed at which the processor is run.

Is this an over-clocking issue?

This problem is observed in flawed chips that are not over-clocked, in chips that have never been over-clocked, and in chips that are run at less than their rated clock speed.

Are other microprocessors affected by this particular problem?

This problem has not been observed on any microprocessors manufactured by Intel or Cyrix.

Test Your AMD-K6-2 Microprocessor

If you are viewing this Web page using Microsoft Internet Explorer V4 or V5 and your computer uses an AMD-K6-2, Athlon, or Duron microprocessor that is flawed in this manner, the problem will be evident when you view the test JPEG image shown on the left. (This JPEG image is displayed properly, even on computers with a flawed AMD microprocessor, when Netscape Navigator is used.)

The image to the right is an equivalent image in GIF format. It always appears correctly and shows how the test JPEG image should appear. On a properly running AMD microprocessor, the JPEG image above left and this GIF image to the right will appear identical.

If both of the images above appear identical when viewed with Microsoft Internet Explorer V4 or V5, then your AMD microprocessor does not have this problem! If you would like to see an example GIF image that shows the distortion that does occur on computers that use a flawed AMD microprocessor, click here.

On an AMD microprocessor that has this flaw, the amount of distortion that occurs when displaying a JPEG image is reduced when the clock rate to the microprocessor is reduced. The two GIF images below document the results that are obtained when a flawed AMD-K6-2 300 MHz microprocessor is operated at 266 MHz and at 300 MHz:

Result at 266 MHz	Result at 300 MHz

This problem is not caused by a fundamental design flaw with the AMD-K6-2 microprocessor, and the vast majority of these microprocessors operate properly. This flaw adversely affects only certain sequences of instructions on some AMD-K6-2 microprocessors. It is strongly suspected that algorithms that have been optimized to use the MMX instructions exhibit this type of problem on AMD microprocessors with this manufacturing flaw. The failure also appears to be data dependant, since some portions of the JPEG image are displayed properly, while other portions of the image are incorrectly decoded.

This problem has been reported by others, using a wide variety of different motherboards and other types of video adapters, including both AGP as well as PCI video cards. Different versions of the manufacturer's video drivers and BIOS software have been used without having any effect on this problem. The problem continues to occur when the Microsoft Standard VGA display driver is used. In all cases, the AMD microprocessor is considered to be the root cause, since replacing only the microprocessor chip corrects this particular problem.

DIAGNOSIS:

It is important to recognize that similar display problems are often caused by software problems, rather than a microprocessor problem. Frequently, a problem with the display adapter's driver or a software conflict may cause similar difficulties. An IRQ or DMA conflict or a problem with the display adapter card or firmware can also present similar problems.

The most conclusive way to diagnose this specific problem is to exchange the AMD microprocessor chip from a computer that exhibits this problem with the same speed and type of AMD microprocessor from another computer that operates properly. If the problem moves from one computer to the other, you may confidently conclude that the microprocessor chip itself is flawed. To correct the problem you must return the microprocessor chip or the computer to the vendor from which it was purchased for a warrantee exchange.

Currently available diagnostic utilities, like American Megatrends’ AMIDiag V5.42A, do not detect this defect in the AMD microprocessor. Although this is an excellent diagnostic tool, the tests run by this diagnostic do not identify this specific problem. Later versions maybe updated to cover this issue.

Since it is often very inconvenient or impractical to exchange a microprocessor that you suspect is defective with a known good AMD microprocessor, you may follow our Software Diagnostic Procedure to better evaluate if a potential microprocessor problem is causing your problem.

This problem was present on our family's computer, and after trying to resolve this with alternative video adapters, display drivers, later BIOS versions, and various Windows updates, it was finally resolved by replacing just the AMD-K6-2 microprocessor. The information published here is based on our experience and that of others who have also had this type of problem and reported it to us. 

After publishing this information on the Internet via these Web pages, we've received email from several additional individuals from around the world who have also experienced this same problem and were able to correct it by simply exchanging their AMD-K6-2 microprocessor with another similar AMD chip. Reports from other PC enthusiasts confirm that this problem also occurs with some AMD-K6-2, Athlon and Duron microprocessors. This problem has been reported with these microprocessors with rated speeds from 300 MHz through 1.2 GHz.