Cyrix Processors
6x86 Processor FAQs


General

Q. What is the Cyrix 6x86™ processor?
A. The sixth-generation 6x86 processor, formerly the M1, is a high-performance superscalar, superpipelined, x86 processor.

Q. How does it differ from the Pentium® processor?
A. Most significant are the architectural differences which result in the 6x86 processor's superior performance gains. While both the 6x86 and Pentium® processors are superscalar and contain an 80-bit floating point unit and a 16-KByte primary cache, other architectural features are found only on the 6x86. The 6x86 processor's integer and floating point units are optimized for maximum instruction throughput by using advanced architectural techniques including register renaming, out-of-order completion, data dependency removal, branch prediction and speculative execution. These design innovations eliminate many data dependencies and resource conflicts to achieve high performance.

Q. Can I use the Cyrix 6x86 processor as an upgrade for my 586 computer?
A. Cyrix doesn't sell the 6x86 processor as an upgrade processor.

Compatibility

Q. Is the 6x86 processor compatible with existing software?
A. Yes. The 6x86 is compatible with x86 software and all popular x86 operating systems including Windows® 95, Windows, Windows NT, OS/2, DOS, Solaris and UNIX. Additionally, the 6x86 processor has been certified Windows 95 compatible by Microsoft. While we cannot test every x86 application available, the Software Compatibility List is updated frequently to provide an index of hundreds of applications and programs that have been tested on systems using the Cyrix 6x86 processor.

Q. Is the Cyrix 6x86 processor certified for Windows 95?
A. Yes. Cyrix tested the 6x86 processor on hundreds of x86 software applications to ensure compatibility with new and existing software. Additionally, the 6x86 processor (up to and including the PR200+ processor performance class) has been certified Windows 95 compatible by Microsoft. We're licensed by Microsoft to use the "Designed for Windows 95" logo.

Q. Can the 6x86 processor run 16-bit and 32-bit software?
A. Yes. The 6x86 was designed to run existing 16-bit software as well as the latest 32-bit software.

Motherboards

Q.Which motherboards work with the 6x86?
A. Refer to the Cyrix recommended 6x86 motherboard list for information on Cyrix certified motherboards for all 6x86 performance classes.

Q.What board MHz setting do I use for each P-rating?
A.PR120+ = 50MHz CPU bus with a 2X clock (50/100MHz)
PR133+ = 55MHz CPU bus with a 2X clock (55/110MHz)
PR150+ = 60MHz CPU bus with a 2X clock (60/120MHz), same as Pentium-120
PR166+ = 66MHz CPU bus with a 2X clock (66/133MHz), same as Pentium-133
PR200+ = 75MHz CPU bus with a 2X clock (75/150MHz)

Q.The motherboard has several voltage settings. Which one is right for the 6x86?
A.It depends on which CPU you have. The markings on top of chip will indicate which voltage setting is appropriate.

Q.How do I know my motherboard can support the 55/110 MHz 6x86-PR133?
A.The board or documentation should have jumper settings defined for 55/110MHz. Refer to the Cyrix recommended 6x86 motherboard list for a complete list of platforms that support the PR133+.

Q.I have found other motherboards that work with the 6x86 but are not on your recommended list. Why not?
A.It could be one of several things: the manufacturer has not given us a sample, has not approved the listing, or it is going through testing now, but has not completed the test suite. Check back -- the list is updated several times a month.

Performance

Q. What are the performance results for the 6x86 processor?
A. We list full, competitive 6x86 performance results for several industry benchmarks. The tests show that the 6x86 processor outperforms higher-megahertz Pentium processors in each performance class.

Q. What is this new performance, or P-rating, system Cyrix is using?
A. The P-rating system was jointly developed by Cyrix, IBM Microelectronics, SGS-Thomson Microelectronics, and Advanced Micro Devices. The P-rating system allows end-users to base purchases on relative PC performance levels rather than just the clock speed (MHz) of the processor. The new evaluation system relates the results of industry-standard benchmarks to what is achieved by an Intel Pentium processor of a given frequency. For example, a processor with a PR150 rating would have performance comparable to a 150 MHz Pentium processor, regardless of its actual clock speed.

Q. Why was the P-rating developed?
A. Clock frequency (MHz), while important, is no longer an accurate or consistent measure of CPU performance. Architectural differences between processor designs add another variable to the equation. With the P-rating in place, a PC buyer can easily evaluate all personal computer processors for a given performance category -- without scrutinizing the architectural merits of the different processors.

MicroDesign Resources (MDR) Labs conducted independent performance testing of the 6x86 processor. Commenting on the P-rating methodology, Michael Slater, president of MicroDesign Resources and publisher of the Microprocessor Report, said, "This is the first comprehensive and credible method for comparing competing processors based on the relative performance they bring PC users under real-world conditions. It standardizes test system configurations based on commercially available components, and it uses the most widely recognized and utilized application-based benchmark tests. I expect the new P-rating methodology to achieve broad industry acceptance."

Q. How does the P-rating work?
A. The P-rating process uses a standardized system configuration and application-based benchmark tests to establish a performance, or 'P,' rating relative to a Pentium processor of a given frequency (MHz). This levels the playing field and allows the measurement of relative processor performance under real-world conditions, regardless of the processor's clock speed (MHz) or architecture.

Q. What benchmark test is used in the P-rating?
A. Ziff-Davis Winstone® 96 is used because it is a real-world, application-based benchmark that contains the most popular software applications (based on market share) that run on a Pentium processor. Winstone 96 also is the most widely used benchmark, and is freely distributed and available.

Q. Why is there a plus mark in each 6x86 processor name?
A. For the 6x86 processor, a "+" designation is used to indicate better performance.

Winstone 96 6x86-PRxxx+ > Winstone 96 Pentium-xxx
xxx = Performance (P) rating

For example, a 6x86 processor with a P-rating of "PR166+" (regardless of processor name and clock speed) indicates performance faster than a 166 MHz Pentium processor. The plus mark indicates performance that consistently exceeds the same Pentium processor megahertz level.

Processor Voltages and Identification

Q.What does the C028, 3.52V (C028), or 3.52V mark on top of the chip mean?
A. C028 or 3.52V (028): The device operates at a nominal voltage of 3.52V. You should use the appropriate voltage settings on the motherboard (often documented as VRE, 3.52V or 3.4-3.6V range). C016 or 3.3V (016): The device operates at a nominal voltage of 3.3V. You should use the appropriate voltage settings on the motherboard.

Q.What is the "6x86L" processor?
A.The "L" brand mark simply refers to the 2.8V 6x86 processor (6x86L). The 2.8V 6x86 processor is a low-power, split-voltage CPU. It operates on a dual power supply (3.3V I/O; 2.8V core) whereas other 6x86 processors are single-voltage CPUs (3.3V or 3.52V). See the Hardware Design Center for further documentation about the 2.8V 6x86 processor.

The 2.8V 6x86 processor uses the same BIOS and pinout as other 6x86 voltages. Motherboard jumper settings must be adjusted for the split-voltage feature. See the Cyrix recommended 6x86 motherboard list for specific model information.

Q.What does the 110MHz on the 6x86-PR133 chip mean?
A.The operating frequency is 110MHz (55MHz bus) but the device has been verified to perform better than a Pentium-133.

Q.Why does the BIOS recognize my 6x86-PR133 chip as a 6x86-PR120?
A.The motherboard jumpers are incorrectly set to 50/100MHz or the motherboard does not support 55/110MHz.

Purchase and Support

Q. What 6x86 processors are currently available?
A. The 6x86-PR200+ (150 MHz), 6x86-PR166+ (133 MHz), 6x86-PR150+ (120 MHz), and 6x86-PR133+ (110 MHz) processors are in volume production now.

Q. How can I purchase the 6x86 processor?
A. Computer manufacturers around the world can buy in volume quantities directly from Cyrix. PC integrators, VARs, dealers, resellers, and retailers can purchase Cyrix processors through an independent Cyrix U.S. distributor or worldwide distributor. End users can purchase a computer that uses the 6x86 from local PC resellers. There is more information available on purchasing Cyrix processors.

Q. What if I have more questions?
A. Please contact the Cyrix Processor Support Desk.

Software and Systems

NOTE: Please see the Cyrix Games and Multimedia Software Compatibility list for the latest information and patches.

Q. When I run Windows 95 on my 6x86 computer, the Windows 95 control panel system information identifies the CPU as a 486. Why?
A. The algorithm used in Windows 95 to detect the CPU was completed before the Cyrix 6x86 was released and therefore the Cyrix 6x86 responds to the algorithm just as a 486 does. To verify that your system is using the 6x86 microprocessor, please reference your computers BIOS startup screen. In addition, the following software utilities identify the 6x86 CPU correctly: Diagsoft QA Factory 6.02 and QA Plus/FE 5.42; Quarterdeck Manifest 4.01; and PC Doctor Rev 1.5.162 from Watergate Software.

Q. What impact will the 486 ID of the Cyrix processor have on my applications?
A. Performance and compatibility in standard office applications is not affected at all. Many games use the Windows 95 ID to determine which processor is being used. Though initially, this caused some problems, most of these have been resolved. Consult the games & multimedia software listing for additional information.

Q. Why isn't there a patch for Windows 95 that will call the Cyrix processor a Pentium?
A. Many applications will try to do Pentium routines if they detect a Pentium Processor. The 6x86 is a Cyrix-designed processor that has unique features that need to be enabled and used properly. Conversely, Cyrix does not support all Pentium routines.

Q. When I run 3D Studio on my 6x86-based PC, the program stalls. What's the solution?
A. 3D Studio uses software timing loops in the code. The 6x86 processor executes these loop instructions faster than previous x86 CPUs which interferes with timing dependent code inside the program. Solution: Download the fstcpufx.exe file from Kinetix, a division of Autodesk. Run the executable patch file and follow the instructions. The patch alters the 3D Studio executable file.

Q. When I run Clipper applications on my 6x86-based PC, the program is stalling. What's the solution?
A. Clipper inserts software timing loops into the applications when the code is compiled. The 6x86 processor executes these loop instructions faster than previous x86 CPUs which interferes with timing dependent code in the program. Solution: Download the pipeloop.exe file and put it in your autoexec.bat file. This utility inserts a delay in the loop instruction.

Q. I'm having problems with my system booting or locking up. What can I do?
A. Cyrix developed the Troubleshooting Tips section to help you quickly resolve common systems issues on your own. Please follow instructions carefully. If you have further questions, contact the Cyrix Processor Support Desk.

Thermal and Heatsink

Q.Why does the processor get hot?
A.All processors produce heat that may feel hot to the touch. This is normal for all electronic components and semiconductor devices.

Q.How much heat does the 6x86 processor produce?
A.The 6x86 processor is a high-performance processor that can dissipate as much as 25 watts of power depending on the CPU clock frequency, an amount comparable to the Pentium® Pro processor. The case temperature range for the 6x86 processor is 0°C-70°C (32°F-158°F) -- the industry standard commercial temperature range for all electronics devices. For full thermal details, see the Cyrix 6x86 Thermal Design Considerations (PDF file, 100 KB) application note.

Q.Does this heat affect the processor?
A.No. When design specifications are followed, the 6x86 processor works properly over the specified operating temperature range.

Q.How is processor heat controlled?
A.The 6x86 processor package is cooled by radiation, convection and conduction. This is achieved by installing a heatsink/fan component. The heatsink/fan radiates heat away from the processor and transfers the heat to the ambient air inside the case. Proper case airflow design removes the heat from the case by maintaining an adequate airflow rate. For full thermal details, see the Cyrix 6x86 Thermal Design Considerations application note.

Q.Does Cyrix provide a heatsink/fan with the 6x86 processor?
A.Yes, on the 3.52V and 3.3V processors, when requested. Cyrix does not provide a heatsink/fan with the 2.8V 6x86 processor. Specifications are supplied to assist the reseller in making the right heatsink/fan purchase.

Q.Does processor heat affect the motherboard voltage regulator?
A.Cyrix tests all motherboards extensively and publishes a list of approved motherboards that support the 6x86 processor. The testing of the voltage regulator is especially important because it supplies power to the processor and other motherboard components. Cyrix-approved motherboards use robust regulators with heatsinks that fully support the 6x86 processor and regulate the current flow precisely.

Q.Does Cyrix have a heatsink/fan solution that is 90 degrees oriented so the voltage regulator can be cooled?
A.Cyrix recommends having an adequate heatsink on the voltage regulator. If further cooling is deemed necessary, the VEMALINE HTS108 solution can be used. This solution can be oriented to blow air to the voltage regulator.

Q.What if I have further questions?
A.Please contact the Cyrix Processor Support Desk with further questions, or see the Cyrix 6x86 Thermal Design Considerations application note.

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