AMD K6-2 Frequently Asked Questions (FAQs)
This page answer questions about AMD K6 microprocessors that PCC customers frequently ask. Questions are answered by one of PCC's staff engineers as a service to assist customers who are typically seeking to find a replacement microprocessor to work with an existing design. Please keep in mind that AMD microprocessors are manufactured by Advanced Micro Devices and that PCC is not affiliated with AMD in any way and AMD should be considered the final authority with respect to AMD K6 microprocessor information. With this said, many of PCC's customers report having difficulty getting answers to questions when asked through official AMD channels due to the fact that the AMD K6 family of microprocessors has been discontinued by AMD. As a result, we will do the best to share our knowledge with you.
Can I use an AMD K6-2 or K6-III microprocessor in my motherboard?
AMD K6-2 and K6-III microprocessors are designed to work in designs that conform to either Socket 7 or Super7 platforms. This applies to AMD K6-2 and K6-III microprocessors that have an E (Embedded) in the part number, as well as those that include a plus sign (+) in the part number. With this said, be sure to read the complete answer to this question below as well as What Power Supply concerns should I have when replacing an AMD K6-2 microprocessor? and Will I damage anything if I plug an AMD K6-2+ or K6-III+ microprocessor in my motherboard if I do not have the correct BIOS?
What's the difference between Socket 7 and Super7?
Socket 7 is a platform that became very popular and gained industry-wide acceptance with many microprocessor manufacturers including AMD, Cyrix, and ITT. Many desktop and notebook computer motherboards, including embedded applications were designed using this specification. If your motherboard is Socket 7 compliant you should be able to use any Socket 7 compatible microprocessor, as long as your motherboard BIOS supports your microprocessor.
Socket 7 had several limitations that were overcome when AMD introduced the Super7 platform. While most of the enhancements introduced within Super7 were primarily of concern to engineers designing new mother boards, Super7 also increased support for the microprocessor clock speed (Front Side Bus) from 66MHz to 100Mhz. This increase allows the end user to gain a significant increase in performance when the Super7 platform can be used.
Other differnces between Socket 7 and Super7 include support for PC100 SDRAM and 2X AGP graphics.
Can I use an AMD K6-2+ or K6-III+ in a Socket 7 motherboard?
To operate at the rated performance of an AMD K6-2+ or K6-III+ microprocessor (Including the E model) you will need to use a motherboard that can operate at the proper front side bus speed. If your motherboard is Super7 compliant it can produce cloce frequencies up to 100MHz which meets all your needs. If you install the microprocessor in one of the original Socket 7 motherboard the maximum clock speed that can be produced by the motherboard will likely be limited to 66Mhz.. As a result, the microprocessor will work, however, it will not operate at its rated speed..
To illustrate this concept, consider this simplified example. If you install a microprocessor rated at 500Mhz in a Super7 or other motherboard that makes a 100MHz front side bus available, the microprocessor can use a 5x multiplier to run at 500 Mhz (5x100). However, if the front side bus speed of your motherboard is only 66MHz as you would expect with Socket 7 motherboards, then the same 5x multiplier will only run the microprocessor at 333Mhz.
You may still be able to benefit from the enhanced instruction set and L2 cache, however, the exact performance improvement would have to be determined by actual trial.
Which AMD K6 microprocessors require using a Super7 motherboard to operate at rated performance?
All AMD K6-2 and K6-III family microprocessors (includes E and + versions) are designed to take advantage of clock speeds higher than 66MHz. As a result, if you are replacing an existing AMD K6-2 or K6-III microprocessor your motherboard will likely already be capable of producing the front side bus speeds up to 100Mhz.
In other words, if you are replacing an existing AMD K6-2 or K6-III microprocessor you likely already have a Super7 motherboard and therefore can expectx to run at the rated performance of the microprocessor as long as your BIOS was designed to work with + (plus) family microprocessors.
Can I replace an AMD K6-2 with an AMD K6-2+ or AMD K6-III+ microprocessor?
Yes, however you may have to do more than just replace the microprocessor. Exactly what you have to do will depend upon your motherboard or existing motherboard design..
In most cases the most important thing to do is to verify that your motherboard can produce the correct supply voltage. AMD K6-2 microprocessors are designed to work with 2.2V whereas Standard AMD-K6-2+ and AMD K6-III+ microprocessors work with 2.0V and Low Power AMD K6-2+ and AMD K6-III+ microprocessors require an even lower power supply voltage. Refer to your motherboard manual for more information.
To run with the rated performance of the microprocessor you may also need BIOS support.
Since you will be replacing another K6-2 microprocessor it is likely that your motherboard already supports a 100MHz front side bus so this is not normally a problem.
Refer to the sections of this document titled What Power Supply concerns should I have when replacing an AMD K6-2 microprocessor? and Will I damage anything if I plug an AMD K6-2+ or K6-III+ microprocessor in my motherboard if I do not have the correct BIOS? for more information.
Can I damage my motherboard or new K6-2+ or K6-III+ microprocessor if I install it in a motherboard that is setup to use the wrong voltage?
Yes. The Standard power AMD K6-2+ and K6-III+ microprocessors are designed to work with the supply voltage between 1.9V and 2.1V. If the power supply voltage ever increases above 2.1V you will exceed the absolute maximum voltage rating of the microprocessor which can cause physical damage. Please be sure to read the VERY IMPORTANT question below for details. Low power versions require even less voltage.
All AMD K6 microprocessor with the + in the part number use AMD's .18 micron process (as compared to AMD's .25 micron process). This is important because parts that use AMD's .18 micro process are designed to operate with lower core voltages as compared to other AMD K6-2 and K6-III microprocessors.
The Standard Power K6-2+ and K6-III+ microprocessors use a core voltage of 2.0 Volts +/- 5% and Low Power Versions use even lower voltages.
If your motherboard is designed to use a higher voltage, such as 2.2V which is used by AMD K6-2 and K6-III microprocessors that use the .25 micro process you may need to "do something" before powering up your motherboard with a K6-2+ or K6-III+ microprocessor.
"Do something" may simply mean move a jumper, as may motherboards allow you to set the core voltage manually. In other cases, "do something" may mean make a minor design change that may include replacing a fixed voltage regulator or other components used to set the supply voltage. If you are not sure what core voltage your motherboard produces you should contact the motherboard manufacturer or your design engineering department.
Will I need to upgrade my BIOS if I replace my existing K6-2 microprocessor with a K6-2+ or K6-III microprocessor?
To take advantage of all the advanced features of K6-2+ and K6-III+ microprocessors your motherboard will need to have BIOS support for the + family of microprocessors. Whether or not your motherboard's BIOS supports the advanced features of the + family is something you will have to determine from your motherboard manufacturer or other sources.
If you have the manual that came with your motherboard look for a list of supported microprocessors and determine whether any of the supported AMD microprocessors have a + as part of the part number. If your motherboard support at least one AMD K6-2+ or AMD K6-III+ microprocessor then chances are good that you can use any of the K6-2+ or K6-III+ microprocessors.
Of course, the proper thing to do is always to first check with your motherboard manufacturer to determine whether your BIOS supports the + family of microprocessors and whether a BIOS upgrade is recommended.
If my existing BIOS does not support K6-2+ or K6-III+ microprocessors is a BIOS upgrade available?
There are several places you can go to get a BIOS upgrade for your motherboard. The first place to look is your motherboard manufacturer's website.
If your motherboard manufacturer can not provide the upgrade you need, you may wish to check with Unicore Software/MR BIOS which has been recommended by AMD.
You can also use your favorite search engine to find other options. I would recommend a search phrase that includes the name of your motherboard's manufacturer and the words "BIOS upgrade" in quotes. If you do not find the information you need, replace the name of your motherboard with the chipset your motherboard uses and search again.
With this said, most end users who use K6-2+ and K6-III+ microprocessors in motherboard that do not have BIOS support for the + series report correct function and substantially improved performance.
No. Hardware problems due to installing an AMD K6-2+ or AMD K6-III+ microprocessor in a motherboard that does not have BIOS support for the + family has never been reported to PCC and is very unlikely.
Which is the fastest microprocessor that I can use to replace my existing AMD K6 microprocessor?
Depending upon the software that you run, the fastest Super7 microprocessor ever made will either be the K6-III+ or the K6-2+.
The AMD K6-III+ microprocessors have 256KB of L2 internal cache compared to 128KB of L2 cache in the K6-2+. At first glance, it would seem that the K6-III+ would therefore be faster than the the K6-2+, however this is not always the case. The reason is that the front side bus speed of the microprocessor must also be considered. AMD K6-III+ microprocessors are available that operate at 500Mhz while K6-2+ microprocessors can be purchased to operate at 570MHz.
As a result, if the software that you run benefits more from a larger internal cache it may run faster with a K6-III+ than a K6-2+. Other software will benefit more from a faster front side bus speed allowing a 570MHz K6-2+ to outperform a K6-III+ that is only running at 500MHz.
K6-2+ microprocessors rated at 570MHz are readily available from PC Components.
What does the E in the part number of an AMD K6-2 family possessor mean?
Advanced Micro Devices (AMD) has produced microprocessors from two internal groups within AMD. Microprocessors which include an E in the part number were produced by AMD's "Embedded" Group. Those that do not have an E in the part number were manufactured by AMD's "Desktop PC" group.
Microprocessors manufactured by the "Desktop PC" group were marketed to compete with microprocessors produced by other manufacturers, especially Intel. The pricing structure, warranty, and support programs offered by AMD were therefore designed to be competitive in this market.
Microprocessors manufactured by the "Embedded" group were marketed to companies who designed products that used a microprocessor as part of its integral design. Typical embedded applications might include a Sony PlayStation, cash register, or Access Control System. To make the product more desirable to these groups AMD offered a long term availability guarantee, lower power and higher temperature versions, and often added addition support and or registers desirable to the embedded market.
It is important to understand that the designation "Desktop PC" or "Embedded" has nothing to do with application restrictions. Parts produced by the Desktop PC group can certainly be used in Embedded applications and vice versa.
The only area of concern that many end users have when deciding whether to purchase a part produced by the Desktop PC group or the Embedded group is that AMD has documented that internal changes are often made to allow Embedded product to operate reliably at higher temperatures or lower voltages, and we know that AMD often offered a longer warranty to embedded customers, but the actual changes made to offer a longer warranty are almost always undocumented.
In addition, some Embedded product enhancements included support for new instructions and/or registers or even functional changes,
There is no standard answer for how Embedded microprocessor differs from non-embedded product. The only way to tell for sure is to compare the data sheets of the specific Desktop PC and Embedded Product. If you will be replacing a microprocessor in an existing design and you do not have the time of ability to compare the individual data sheet you can play it safe by using an Embedded microprocessor as the Embedded part is always the same or a better part.
Can I use a K6-2E+ or K6-IIIE+ to replace a non-embedded microprocessor that does not have an E in the part number.
Yes. What is important when replacing a microprocessor is that the Embedded series (E) can always replace a Desktop microprocessor but not necessarily the other way around.
The "Embedded" series of K6-2E+ and K6-IIIE+ microprocessors are backwards compatible with the "Desktop" K6-2+ and K6-III+ microprocessors. They include certain enhancements to improve performance, compatibility, and reliability as described in the AMD K6-2E+ data sheet but these changes will not cause problems in older applications.
AMD added new registers to provide expanded support. Refer to the AMD K6-2E Registers Table of the AMD K6-2E+ and K6-IIIE+ data sheet for more information.
I ordered an Embedded microprocessor but the part I received does not have an E marked on the part. How can I be sure I received the correct part?
AMD includes the E in the AMD Ordering Part Number (OPN) although the E often does not appear on the part. This is unfortunate and certainly is confusing. The only way you can tell whether your microprocessor is actually an E version is to buy it from a trusted supplier. Another good measure to avoid mistakes is to reference the AMD DS number.
The following AMD DS (internal part numbers) were provided to PCC by AMD in written correspondence between our two companies:
|AMD K6-2E Ordering Information|
|AMD Internal Part Number||AMD Ordering Part Number (OPN)||Part Marking|
|DS91899||AMD K6-2E+/450ADK||AMD K6-2+/450ADK|
|DS91892||AMD K6-2E+/475ACZ||AMD K6-2+/475ACZ|
|DS91893||AMD K6-2E+/500ACZ||AMD K6-2+/500ACZ|
|DS91897||AMD K6-2E+/533ACZ||AMD K6-2+/533ACZ|
|DS91895||AMD K6-2E+/550ACZ||AMD K6-2+/550ACZ|
|DS91896||AMD K6-2E+/570ACZ||AMD K6-2+/570ACZ|
The ordering information indicates the letter R designates Case Temperature. The part number for my K6 that I want to replace ends with an R. Can I replace this with a part that has a Z suffix? What does Case Temperature actually mean?
Case temperature is the absolute maximum temperature that the microprocessor can be operated at without adversely effecting processor life or reliability. To measure the case temperature you should attach a thermocouple to the top center of the microprocessor with thermally conductive epoxy. If a heat sink is used you should drill a small hole in the top center of the heat sink and insert the thermocouple into this hole and secure with thermally conductive epoxy. Measure the temperature with the device warmed up and at operating temperature with the outside air (room temperature) at the maximum room temperature that the system will be operated.
AMD Case Temperature Suffixes
R = 0 to 70 degrees C
Z = 0 to 85 degrees C
This means you can always replace a part with an R suffix with a part with a Z suffix as long as you use the same heat sink and fan, and as long as they are properly attached. This is because the part you will be replacing is only designed to operate at 70 degrees max, so there is no problem using a part that can be operated at temperatures up to 85 degrees.
If you want to replace a Z part with a part with an R suffix you may need to use a different fan or heat sink. The only way to know for sure would be to measure the case temperature as described above.
What is the difference between CPGA and OBGA packages and are they interchangeable?
AMD K6 microprocessors may be available in a Ceramic Pin Grid Array (CPGA) or Organic Ball Grid Array (OBGA). We recommend replacing K6 microprocessors with microprocessors using the same package, unless design engineers are available to review the application. The OBGA package includes additional pins not supported on the CPGA package which means designs using a CPGA package in an OBGA design may not work if the additional pins are used in the application. Furthermore, there are differences in how Standard and Low Power microprocessors work that can cause complications if not reviewed. Refer to the AMD data sheet to determine specific information.
Can I operate a standard power AMD K6-2+ microprocessor at 2.2 Volts?
All standard power AMD K6-2+ microprocessors are designed to be operated at 2.0V +/- 5%. This means 2.1V is the highest permissible voltage. Due to the fact that so many earlier processors use 2.2V many end ask PCC whether the K6-2+ can be operated at 2.2V. Other end users have reported to PCC that they have successfully used 2.2V without apparent problems.
PCC's policy is that end users who use K6-2+ or K6-III+ microprocessors at 2.2V do so at their own risk. Due to the fact that 2.2V is within 10% of the nominal voltage specified we are not surprised to hear success stories, however, we recommend to end users who take this risk they they measure the operating temperature of the microprocessor in the top center of the heat sink in accordance with AMD's procedure and take measure to insure that the maximum operating temperature is not exceeded.
You can be certain that the part will run hotter at 2.2V than it does at 2.0V but the question is will it get too hot, as determined by the maximum allowable case temperature specification (refer to the last digit of the part number).
If you find you need to reduce the case temperature there are several things do. You can use a larger heat sink, increase air flow by using a different or second fan, and you can reduce the room temperature. (Did anyone see the movie the China Syndrome?).
Can the K6-2+ and K6-III+ microprocessors be overclocked?
PCC does not support overclocking however customers frequently report that they successfully overclock these microprocessors. PCC recommends customers who wish to operate K6 family microprocessors at faster than rated clock speeds start with the fasted microprocessor they can find and then refer to AMD users group and blogs online for help and support. With this said, customers who overclock do so at their own risk.
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