For many, computer upgrade options are quite limited, especially for those with prebuilt systems from big name manufacturers. These manufacturers often use proprietary motherboards and/or cases, meaning that all you can do is upgrade the RAM and maybe a few other components. Video or sound integrated on the motherboard complicates those upgrade options even further.

At first glance, it seems like upgrading a Socket 7 based system should be easy - just pop in another Socket 7 CPU and adjust the motherboard settings where necessary. Even AMD makes it sound like this is a possibility in their own K6-2 FAQ. To quote them directly regarding their stance on using a K6-2 in a Socket 7 motherboard:

Question:
Is the AMD-K6.-2 processor compatible with the popular Socket 7 platform?

Answer:
Yes. Socket 7 represents the vast majority of today's installed base of PCs and has been proven for reliability, upgradeability, and low cost. For even better system performance with the AMD-K6-2 processor, choose a Super7 motherboard. Before selecting a motherboard you should first check with the manufacturer and review the recommended AMD motherboard support list.

Of course, things are never quite that simple. What AMD has neglected to mention explicitly, and has only alluded to briefly in the last sentence, is that Socket 7 CPU's do not all have the same requirements from the motherboard. Delving a little deeper into AMD's K6-2 specifications, it quickly becomes clear that there is more to it than just dropping in a new chip. Essentially three things are required to perform a Socket 7 CPU upgrade:

1. The motherboard must support the correct CPU voltage
2. The motherboard BIOS must be able to recognize the processor
3. The motherboard must support the correct bus speed and clock multiplier settings

This is pretty much the case regardless of which Socket 7 CPU is preferred for an upgrade. Clearly, there is a lot more involved than just lifting the lever on that ZIF socket and switching chips. In fact, the chances of upgrading a motherboard designed without the K6-2 in mind are slim to none.

Enter the PL-ProMMX kit from Powerleap that promises to solve all these issues on most Socket 7 motherboards, allowing upgrades up to 400MHz.

The biggest hurdle involved in a Socket 7 CPU upgrade is the hardware limitations of the current motherboard, including the voltage and clock multiplier support. The PL-ProMMX takes care of these issues with a small adapter that sits between the motherboard's Socket 7 (or even Socket 5) and the new CPU, which plugs into the adapter board's own Socket 7. On this little adapter is a switching voltage regulator with four 1500uF capacitors and a toroidal inductor. This voltage regulator module is powered via a standard 4-pin power connector from your power supply.

Five jumpers control the CPU voltage from 1.6V to 3.5V in 0.1V steps. Three more jumpers control the CPU's clock multiplier from 1.5x to 6x. Finally, there is a jumper for toggling CPU temperature monitoring support.

The included fan and heatsink are both of very high quality and do an excellent job of keeping the CPU cool. The fan is a ball bearing design, which should help to insure it will last a long time. Unfortunately, it is not the quietest CPU fan I have ever seen, but certainly not the loudest either.

Since the adapter can only deal with electrical and clock multiplier issues, BIOS support is still a potential downfall. A list of compatible systems and motherboards is available from Powerleap's website and many incompatibilities can be resolved with a simple BIOS flash from the system or motherboard manufacturer. According to Powerleap and AMD, almost any system with one of the following BIOS's can be upgraded successfully:

Award Compile dates of March 1, 1997 or later
AMI CPU Module 3.31 or later
Phoenix Version 4.0 Release 6.0 or Release 5.1 w/build dates 4/7/97 or later

Simply having a "compatible" BIOS does not mean that a K6 series CPU will be recognized as such. What it does mean is that the system will be able to successfully boot up, but the CPU may not be properly recognized - commonly as a 486DX2/66 for example.

A small utility is included that will enable the K6's performance enhancing "Write Allocate" feature for those system BIOS's that do not recognize the K6 as such. This is necessary to utilize the full performance potential of the K6 series CPU's. Note that this utility software is only designed to work on Windows 95, 98 and NT, so alternative OS users will not be able to take advantage of the full performance potential of the K6. We'll take a closer look at this utility a bit later.

Installation

The kit AnandTech received featured an AMD K6-2/333 already installed in the voltage/clock multiplier adapter with a fan/heatsink mounted on top of the whole package. All jumpers came preset for a 5x multiplier and 2.2V core voltage - exactly how it should be for a K6-2/333 running on a 66MHz bus.

If you are running at 50MHz or 60MHz bus, you can either reconfigure your motherboard to run at 66MHz if possible, or use a different multiplier on the adapter. For example, 5.5x60MHz will still give you 330MHz. If your motherboard supports higher bus speeds, such as 75 or 83MHz, you can also reconfigure the multiplier and use those bus speeds. Note that the included CPU's highest multiplier was 5.5x, so users stuck at a 50MHz bus will only be able to get up to 275MHz.

The included manual guides you through the installation process with step by step instructions and good pictures. With the kit, you just lift the lever on your ZIF socket to remove your old CPU and heatsink. Next, drop in the Powerleap assembly and finally put the ZIF socket lever back down.

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The next time you boot up, you will find out how much support your BIOS has for the K6-2. If it is recognized as a K6-2 or K6-3D, then the BIOS should fully support the CPU and the utility software will not be necessary. If the BIOS says 486DX2/66 for example, rest assured, everything will function fine, but the included utility software will be necessary to turn on some of those K6 features. Installing the utility software is just a matter of running the setup program and clicking next a few times.

Utility Software

The Powerleap CPU Control Panel, shown at right, actually has quite a few features and fully support Windows 95, 98, and NT. It's primary function is to enable performance enhancing features of the upgrade CPU if the BIOS does not recognize the CPU and automatically enable these features. In the case of the K6-2, this is the Write Allocate feature that enhances performance.

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The CPU Control Panel can run at Windows startup and automatically quit after enabling any features you select. It can also run in the background, minimized to the system tray, which gives access to the CPU temperature monitoring feature of the PL-ProMMX. There is no way to directly see the CPU temperature, but it can give a warning if the CPU is overheating.

There is also an option to enable "Rain CPU cooling technology." What Rain does is tell the CPU to execute a halt instruction when nothing else is going on, allowing the CPU to run a little cooler. Since it only occurs in unused CPU cycles, there is no performance loss. With the CPU Control Panel, Rain can automatically be enabled if the CPU is overheating as well. This mode of Rain will slow down the CPU if it becomes too hot.

The Test

This is what we've all been waiting to find out about the Powerleap kit and the primary reason for considering it as an upgrade solution. The Test System Configuration was as follows:

• Intel Pentium 133MHz
• Powerleap PL-ProMMX AMD K6-2 333MHz
• IDT Winchip 2 3D 200MHz
• Abit AX5 i430TX Socket 7 motherboard w/ 512KB Cache
• 2 x 32MB 10ns PC66 Hitachi SDRAM
• Western Digital Caviar AC35100 - UltraATA
• Diamond Stealth 3D 2000 - S3 ViRGE (2MB EDO DRAM)
• Metabyte Wicked3D Voodoo2 (12MB EDO DRAM)

This configuration was carefully selected to represent a fairly typical configuration that AnandTech readers might have.

The Abit AX5 was selected as a common motherboard that is not capable of taking a K6-2 due to voltage constraints. It's BIOS detected the CPU as a K6/3D processor and enabled Write Allocate automatically. The Powerleap kit was also installed in an Abit IT5H i430HX motherboard, where it also worked fine.

With RAM being so cheap these days, we decided to use 64MB SDRAM - any system with less than 64MB would benefit the most with a RAM upgrade before a CPU upgrade. Since the performance difference between SDRAM, EDO, and FPM is negligable, AnandTech chose to use SDRAM due to its abudance in today's market.

The Western Digital Caviar is simply an extremely popular hard drive and, again, systems with extremely slow hard drives would benefit the most by upgrading to a faster hard drive.

The S3 ViRGE was selected as a video card for its abundance as a video solution often integrated into motherboards and sometimes cannot be upgraded. A Voodoo2 was used as the 3D card in the system since anyone can add a Voodoo2 to their existing system for minimal cost and with minimal compatibility issues these days. For 3D gaming, a Voodoo2 will provide much more of a performance boost than a new CPU.

An IDT Winchip 2 3D was featured as an alternative CPU upgrade. The Winchip 2 3D uses 3.3V, which allows for compatibility, voltage wise with just about any Socket 7 motherboard. BIOS compatibility and clock multiplier issues remain with older motherboards, however. Check out AnandTech's complete IDT Winchip 2 3D Review for more information.

Other configurations should give approximately the same relative performance boost.

The following drivers were used in the tests

• Windows 98 built in S3 ViRGE
• 3Dfx Voodoo2 Reference Drivers 2.1
• DirectX 6.1

The benchmark suite consisted of the following applications:

• Ziff Davis Winstone 99 under Windows 98
• Quake 2 v3.20 using demo1.dm2 and Brett "3 Fingers" Jacobs Crusher.dm2 demo

All Winstone tests were run at 1024 x 768 x 16 bit color, all gaming performance tests were run at 800 x 600 x 16 bit color. 3DNow! support was enabled when applicable.

Performance Issues

There are a few things that must be considered before looking at the actual numbers. Remember that most K6-2 benchmarks out there are based on the Super 7 motherboard platform, which means support for 100MHz bus speeds and AGP graphics cards. Obviously, these things cannot simply be added to existing motherboards. Thus, these benchmarks will be running on a 66MHz bus with PCI graphics cards. That means that the cache will also be running at 66MHz, 33% slower than what AMD intended for the K6-2.

The cache speed issues can be taken care of in the future if Powerleap decides to release an upgrade kit based around the K6-3, which features 256KB on chip, full speed cache. It has been demonstrated time and time again that cache speed is much more important than bus speed, so the K6-3, with its full speed cache, would make the bus speed a moot point. The current voltage/clock multiplier adapter should be fully prepared for the K6-3 upon its release.

Business Performance

Performance of the Powerleap PL-ProMMX K6-2 on this TX motherboard is pretty close to that of a K6-2 on a brand new motherboard. It is limited somewhat by the ViRGE graphics card used and the 66MHz cache speed. Nonetheless, the performance increase is clearly quite large and the difference can definitely be felt right away.

Gaming Performance

As we've seen time and time again, that K6-2 FPU is not the greatest, but give it a game that takes advantage of 3DNow! and it really flies. With 3DNow! and a Voodoo2, the performance almost matches that of the Pentium Pro Overdrive. It also becomes clear here that a Voodoo2 will do much more for an unaccelerated system than a new CPU ever could.

Other Notes

Powerleap also sells just the voltage/clock multiplier adapter board, which will allow you to use just about any Socket 7 CPU in any Socket 7 motherboard. The same CPU Control Panel utility is included and supports all current AMD, Cyrix, and IDT chips.

Intel motherboards are completely incompatible with non-Intel chips thanks to a routine in the BIOS that checks for an Intel CPU and refuses to boot if one is not found. A 3rd party BIOS upgrade can take care of this issue. Check the Powerleap Compatibility List for more information on compatibility with Intel motherboards.

Some motherboards with jumperless CPU setups can get a bit confused when one of these upgrades is inserted. On Abit boards, make sure you disable speed error hold or else you will get an error that the CPU is unworkable from the BIOS. There is no reason for concern, however, because this simply stems from the fact that the detected CPU speed does not match the settings in the BIOS.

Clearance around the CPU socket is another potential area that might prevent the use of the Powerleap kit. The voltage/clock multiplier adapter sticks out a few millimeters beyond the CPU socket and could interfere with other components on the motherboard. Another potential problem is clearance above the new CPU since the adapter increases the required height. The Powerleap Compatibility List includes many of these potential issues for various systems.

While the chip worked mostly fine at 333MHz, it was impossible to resist taking apart the package that Powerleap had provided. What AnandTech found upon removal of the fan/heatsink was a K6-2 processor rated at 300MHz, not the 333MHz specified on the package. Powerleap is NOT advertising an overclocked package. While it was probably just an honest mistake, it may be worth the extra two minutes or so required to remove the fan and take a look at what processor is actually included.

Update: We spoke with Powerleap about the inclusion of an overclocked processor in AnandTech's review sample and they confirmed that it was a simple mistake. They assured us that they do not sell anything that is overclocked.

Stability in the overclocked 333MHz configuration was below average, but at the rated speed of 300MHz, stability was the same as before installing the upgrade. A true 333MHz CPU in the upgrade package would probably provide the same stability that AnandTech observed at 300MHz. Also note that stability can also be greatly affected by other system components, probably more so than by the upgrade kit.

Conclusion

Unlike the Winchip 2 3D from IDT, the PL-ProMMX kits from Powerleap are available with up to 400MHz K6-2 processors. Future kits may include the K6-3 running at even higher clock speeds. While the Winchip 2 3D is significantly less expensive, it simply is not available in the clock speeds that the K6-2 is. Thus, the Winchip 2 3D may function as a quick and dirty upgrade, but for some real horse power, pick the PL-ProMMX.

So who should purchase the Powerleap PL-ProMMX? The cost of the adapter board and CPU direct from Powerleap is not significantly different from purchasing a new CPU and motherboard. A new motherboard would also bring the benefits of the 100MHz bus, AGP, and, in some cases, SDRAM, UltraATA, and USB.

For others, buying a new motherboard and CPU is not a cost effective option since the old case, RAM, and sometimes onboard motherboard features cannot be transferred to a new board. Those with more proprietary systems from IBM, Compaq, HP, and others also have few upgrade options without scrapping the whole system. For these people, the Powerleap PL-ProMMX is an excellent solution that will bring just about any Socket 7 system up to speed with minimal installation hassle.