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Cover Story
The Uptake on Upgrades

-- by David Gabel

While preparing this review, we had occasion to try to upgrade all our test machines from standard Pentium to MMX chips. This raises an interesting question: Can you upgrade existing PCs to MMX technology?

The answer is a qualified yes. If your motherboard complies with a connection specification for the Socket 7 processor, then you can probably upgrade.

You can tell if your motherboard complies by looking at the socket that houses the processor. It will be a large piece of white plastic holding a large chip (probably topped with a heat sink) and a metal handle on one side. If the plastic cradle has "Socket 7" embossed on it, your motherboard is Socket 7-compliant.

That's the first hurdle. Now you have to get the processor (probably not available except to system builders as you read this) and install it.

Should You Move to MMX?

Herein lies the hitch: The MMX processor uses different voltage levels than does the plain-vanilla Pentium. Both use 3.3 volts to power their I/O pins, which enables those pins to receive signals from the rest of the computer. But the MMX chip's internal core-logic portions are powered at 2.9V to save power and reduce heat generation. That means motherboard makers had to develop a way to get the lower voltage to those pins. They do that with separate voltage regulators. These ancillary regulators often have jumper settings that you use to set the voltage for different processors, both Intel's and those of other manufacturers. If your motherboard has the jumper (newer boards do, but older ones don't), you have to know which jumper to set, information that was probably provided by the system vendor in its documentation. Otherwise, check your vendor's Web site.

You may also have to remove some voltage-regulator modules. Again, check with your vendor. The chipset must support MMX extensions (all Intel chipsets will, but you'll have to ask if you're using another vendor's chipset)

For one of our review systems, the vendor neglected to tell us to change jumpers. As a result, we were running the MMX processor in an overvoltage condition. Fortunately, it didn't affect our testing results. But it will reduce the lifetime of the chip, and if you do it, Intel will probably void your warranty.

Finally, Intel says that it expects to have an Overdrive processor for MMX early this year.

Windows Magazine, February 1997, page 104.

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