Review of the IBM 6x86L
Differences between
the 6x86L and the 6x86The major difference between the 6x86L and the 6x86 is the technology used to manufacture it. The 6x86L is a dual or split-rail microprocessor that is manufactured using a .35 micron process. This process uses CMOS and voltage reduction technology for low power and high density. Because it is a more advanced process technology than earlier 6x86s, the silicon yields significantly more 6x86L P200+ parts than the 6x86 P200+. Lower power and faster parts.
Dual voltage processors have different voltage requirements for the cpu core and the cpu bus interface (core 2.8v, I/O 3.3v). The 6x86L, M2, and Pentium MMX are all dual voltage chips. If your motherboard doesn't have dual voltage support, you cannot use these chips without an external voltage regulator. You can, however, use a single voltage processor in a dual voltage motherboard. Check your motherboard manual to see if your motherboard supports dual voltage supplies. The Official 6x86 Motherboard Compatibility List has also been updated with dual voltage 2.8V compliant motherboards that are certified to run the 6x86L.
To maximize the life and upgradability of your motherboard, do yourself a favor and buy a motherboard has dual voltage support. I can't stress this enough.
Warning! Don't run the 6x86L as a single 3.3V or 3.52V 6x86. You risk damaging your cpu if you do so. The 6x86L recommended maximum core voltage is 2.97V and the absolute maximum core voltage rating is 3.3V. If you have a single voltage motherboard you must use a single voltage 6x86.
The days of heat related 6x86 problems are over with the introduction of the 6x86L. Heat will no longer be an issue worth discussing. The 6x86L consumes much less power and generates much less heat than its older 6x86 brethren. I dumped the whiny Cyrix supplied heatsink/fan that I was using with my Cyrix revision 2.6 P200+ because the 6x86L can operate with any standard Pentium heatsink/fan. My system is significantly quieter now. Although neither Cyrix nor IBM ships a heatsink/fan with the 6x86L, this does not mean that you do not need one. You definitely need a heatsink/fan as an additional cooling measure.
The 6x86L is also a more likely candidate to be successfully overclocked as a result of the fact that it runs very cool and overheating caused by overclocking is less of a problem.
You will not see a performance increase with the 6x86L over the 6x86. The 6x86L processor logically functions the same way as previous versions of the 6x86.
Yes, I know that this is what all of you really want to know. I have received literally dozens of emails inquiring about the IBM 6x86L P200+ at 83MHz. Does it work? No, not reliably. I can boot Windows 95, connect to the net, and run applications for hours. This is great if you don't mind a random GPF every now. The GPFs primarily occur in core Windows 95 virtual devices and system files such as kernel32.dll and msvcrt40.dll. Complete system lockups were rare.
I literally tried every combination that I could think of to resolve the problem. I tried less aggressive memory settings, I turned off the external cache, I bumped up the I/O voltage, I reduced the core and I/O voltage, and I reduced my harddrive speed. The only thing that I didn't do is try 50ns EDO RAM because I don't own any. I don't have any confidence in the Mustang R534 with SDRAM so SDRAM wasn't even an option.
I did get a taste of the speed. I must admit that it was fabulous. However, given the choice between speed and stability, I prefer rock solid stability every time.
Are you disappointed? Honestly, I know of only a couple 6x86 owners out of the tens of thousands that visit this page who have been able to get their 6x86 to run reliably at 83MHz. 83MHz is a tough nut to crack. Don't plan on buying a 6x86L P200+ and overclocking it to 166MHz.
I said that I would answer questions about the 6x86L that I received by email. Here are a few that I did not already answer in the previous sections.
A. Yes. I will be performing my first Windows NT 4.0 benchmarks/test over the next few weeks. I have set up a IBM 6x86L P166+ in a ABIT IT5H running Windows NT 4.0 for this purpose.
A. Demand is currently exceeding the available supply of the 6x86L and some vendors are charging a premium. I think that it is worth paying slightly more for the 6x86L over the 6x86.
A. IBM quality assurance gave the go ahead to the 6x86L and their stock became widely available on 02/13/97. Give my sponsor Real World Technologies a call and tell them that you want a 6x86L. I recommend them highly.
A. The cpus are exactly the same. The differences between the Cyrix 6x86L and the IBM 6x86L exist in company policies about quality control, pricing, and support.
A. Yes, there is one new instruction and one new register. A compare and exchange 8 bytes instruction has been added for compatibility with the next generation of software. A CR4 register has also been added to include the DE (Debug Extension) bit 3 in CR4. See the Addendum to the 6x86 Microprocessor Data Book which describes the 6x86L processor product family of 6x86 cpus for additional information.
A. It is available in many countries throughout the world.
A. Stepping 2, revision 2 is a revision 4.2. This is the current Cyrix and IBM revision of the 6x86L. People, it is time to stop thinking about revision numbers. They are confusing. This was necessary a few months ago, but not any longer. With the introduction of the 6x86L there is no longer a need to worry about them. Ask for a 6x86L and verify that you have received one by identifying the 2.8V label written on the top of it. The Award bios (I'm not sure about the others) will also identify the cpu as a Cyrix 6x86L at bootup.
A. Ask for a ball-bearing heatsink/fan that has a clip so you can attach it to the zif socket. Don't let anyone try to sell you a sleeve-bearing.
A. Dialogue with others and my personal experience indicate that they can. The P200+ is the exception in most every case. I am able to overclock my IBM 6x86L P166+ to a P200+ reliably in a ABIT IT5H motherboard. However, don't assume that just because you buy a revision 3.7 or 6x86L that you can overclock it. This is a very bad assumption to make. As a rule of thumb, buy as much processor as you can afford and be content with your purchase
A. It is equivalent, but not identical to Intel's Pentium MMX fabrication process. I doubt that this will last for long. Intel is normally always one full generation of manufacturing technology ahead of everybody else.
A. Definitely, M2 progress is moving along faster than Cyrix and IBM initially expected.
A. Yes, Cyrix and IBM plan to release a 6x86L 166MHz before the end of the year. Now we find an inherent flaw in the P-rating. What is the comparable Pentium chip when one does not exist?
The IBM 6x86L P200+ is a permanent addition to my personal system. The 6x86L is simply the best 6x86 that has been manufactured to date. If I were buying today, there is no way I would buy a pre-revision 2.7 6x86. It doesn't make sense. Pre-revision 2.7 6x86s are dinosaurs. I would buy a revision 2.7/3.7 6x86 only if it was cheaper than the 6x86L. Go with the 6x86L if your motherboard will support it.
Here is a link to obtain additional information about the IBM 6x86L: