Disclaimer: This FAQ is provided as-is with no warranty. All information in this FAQ as been carefully assembled and reviewed, and is believed to be accurate. However, the information contained is based on limited testing and therefore no representation is made on accuracy or applicability of any information herein. The modifications described in this document may void your product�s warranty. You take full responsibility for a void warranty or damage to a motherboard or connected equipment caused by any information in this document. This document may be freely distributed if unmodified.

CONTENTS:
PART 1: Overview of �Memory mis-detection/CONFIGMG�
PART 2: Overview of �Lost CMOS�
PART 3: The (best-known) solution
PART 4: Summary of testing and research
PART 5: Revision History

PART 1: Overview of �Memory mis-detection/CONFIGMG�

Q: What is the Memory mis-detection problem?

A: In some situations, some motherboards will detect more memory DIMM�s than are actually installed.

Q: How can I tell if I have memory mis-detection?

A: To see if you have this problem, look on the second POST screen. Press the �Pause� key on your keyboard (usually next to Scroll Lock key) to stop the screen for a better look. (Press the Esc key or boot to a floppy if your operating system hides this screen too quickly.)

You can tell if you have this error because you will see �DDR at DIMM(s): 0 1� or �DDR at DIMM(s): 1 2� when you have only one chip, or �DDR at DIMM(s): 0 1 2� if you have two chips.

Q: What is the CONFIGMG problem?

A: When the memory is mis-detected, Windows 98 will give a �CONFIGMG� error on boot-up in some situations. Other versions of Windows or other operating systems will usually show a somewhat different error message, but the net result is that Windows will not start.

Q: What causes the �CONFIGMG� error?

A: The cause appears to be a detection of more memory modules than are actually installed. It is thought that the detection of an extra memory module causes ACPI�s active area to be located in non-existent memory, which stops ACPI from working properly. This then makes Windows report a CONFIGMG error because it cannot configure with ACPI.

Q: Why does this problem cause Memtest86 errors?

A: The listing of an extra memory chip will cause Memtest86 to list more total memory than what is actually installed. Memtest86 will then attempt to test the non-existent memory. Naturally, this causes errors, starting in Test #1. These errors are NOT related to the Data Corruption problem as outlined in the Data Corruption FAQ.

Q: I only have this problem on Cold Boot/Warm Boot/in the morning/sometimes, etc. Why?

A: The Memory mis-detection (and resultant CONFIGMG error message) will often only occur in a limited range of temperatures on the 735 chip. Because the temperatures vary from board to board, you may only see problems on a cold boot when your 735 chip is cool. Other motherboards may only show this problem after they are turned on for a few minutes. Still others might only show the problem after time when the temperature of the environment has changed, or when dust accumulates in the case, causing a change in temperature.

Q: I got the Memory mis-detection/CONFIGMG errors while using DDR memory, then I switched to PC133, and the problem went away. Doesn�t this mean that the problem is with DDR memory, or at least my stick of DDR memory?

A: No. The problem only seems to occur with any DDR memory with 16 chips (see below).

Q: Does all DDR memory cause the problem to show?

A: It appears that most DDR memory will show the problem on a �bad� board. Some tests have found that low density DDR modules (such as 128MB modules with only 8 chips) do not usually show the problem.

Part 2: Overview of �Lost CMOS�

Q: What is the �Lost CMOS� problem?

A: The motherboard will show an error message on boot-up that says something like �CMOS battery low, CMOS settings lost, Press F1 or F2�� This is normal after using the �Clear CMOS� jumper, but shouldn�t happen spontaneously. On motherboards with this �problem� the CMOS settings will be lost repeatedly, apparently without cause. The frequency of loss varies from once every few weeks to every day, depending on the board.

Q: What is the cause of the �Lost CMOS� problem?

A: The cause is not known, but it appears to be fixed when the Memory mis-detection/CONFIGMG error is fixed as shown in the next part of this FAQ.

PART 3: The (best-known) �solutions�

Q: What can I do to fix this problem?

A: There are several options:
1) Apply the �R182 fix.� (See here for details)
2) PC133 memory always seems to be detected correctly. Try using PC133 instead of DDR memory.
3) Use 128MB DDR memory modules with only 8 chips. These sometimes are detected correctly on problem boards. The more common 256MB or 512MB DDR modules with 16 chips make the problem show.
4) Exchange your motherboard. The author�s testing indicates that only a few percent of motherboards are effected by this problem, so an exchange is likely to provide a complete solution.
5) Turn off ACPI. This is not recommended, but does mask the problem enough to allow Windows to boot in many situations. (It is not know if this also works around the �Lost CMOS� problem as well.)
6) Some boards only have the problem when the SiS 735 chip is cool. Turn your computer on and wait for a few minutes in the BIOS screen. Then exit the BIOS and let it finish booting. This will allow the SiS735 to warm up. (You may still suffer from �Lost CMOS� with this work-around.)

PART 4: Summary of testing and research

Test Setup:
Various BIOS versions, up to and including 011215s.rom
AMD Approved Power Supplies from several brands, 300 and 350W PC2100 DDR memory
4 boards with sticker marked �6� near the PCI slots, all known to have the problem.

Test Results:
So far, more than 10 boards with the Memory mis-detection/CONFIGMG problem have been 100% corrected with the �R182 Fix�

Of those boards, two were observed to have the �Lost CMOS� problem. Only one of these has ever lost CMOS settings (and only one time) since the �R182 Fix� was applied.

In an effort to isolate the problem, 3 boards had the 735 heatsink removed and were attached to a temperature controlled aluminum block that was placed on the 735 chip with thermal compound between the two. The motherboards were rebooted many times at different temperatures on the 735 chip. It was found that the problem happened over a range of temperatures, different for each board, but all in the 15-40C range.

PART 5: Revision History

1/8/02 � V1.00 released