Pentium, Pentium Pro, or Pentium II? Intel, AMD, or Cyrix? MMX now or later?
Pick the right PC with this no-nonsense guide to today's-- and tomorrow's-- new CPUs.
For a while, everything seemed to make sense. You knew that a Pentium was faster than a 486, and that a 200-MHz processor was faster than a 133-MHz chip. So if you were shopping for a PC, you simply went for the fastest chip with the highest clock speed you could afford, and went home satisfied. That's all changed.
Now there's a flood of new CPUs on the market, and plenty more
on the way. Thumb the pages of PC World and you'll find systems
sporting a Pentium, a Pentium with MMX technology, or a Pentium
Pro--and perhaps a preview of upcoming Pentium IIs. You'll also
find computers using comparable chips from Advanced Micro Devices
and Cyrix, most of which have their own clock speeds and
characteristics. And there's word of all sorts of new processors,
with river- and park-themed code names like Deschutes, Katmai,
and Willamette, that will muddy the waters even more.
Collectively, these new chips have confused the rules we use to
gauge relative performance. For example, Intel's Pentium MMX is
faster than the Pentium Pro when running 16-bit applications, but
slightly slower with 32-bit programs. And clock speed is no
longer a reliable measure of performance. Witness systems using
the Cyrix 6x86-PR200+: They run at 150 MHz but outperform most
200-MHz Pentium-based machines.
Feeling a little dizzy? Relax, take a deep breath, and let us be your guide through the rapids of constantly changing CPUs.
Chip Choices
Off the Old Block
Under the Hood
The Contenders
On the Horizon
Where the CPUs Stand (chart)
Test Report: How the Top CPUs Perform (chart)
Test Report: MMX Boosts Performance (chart)
Features Comparison (chart)
Anatomy of a Chip (chart)
Plug-In Upgrades
NT Spoken Here
MMX Pentiums: Big Gain, No Pain (2/97)
MMX Upgrades Whip Old PCs Into Shape (4/97)
Top 20 Budget Desktops (4/97)
Tips for Managing Your Navigator Bookmarks
Quarterdeck's Latest Memory Manager Wrings Performance from
Windows 95
More Daily News
One thing hasn't changed: The name of the PC game is still price
and performance. And not only is the CPU a major factor in
determining the speed of your PC, it's also one of your
computer's most expensive components.
The good news is, all these choices are resulting in some real
bargains. As new chips arrive, old ones get cheaper. If you're
willing to settle for, say, a 120- or 133-MHz Pentium, you'll
find complete systems for very little money. "We'll see very
aggressive pricing," says Kevin Hause, an analyst with
International Data Corporation in Mountain View, California.
"Look for more $1000 Pentium-based systems--and that's with
a monitor."
Over the past few months, PC World has looked at a wide variety
of systems and CPUs and has talked to all the major players and a
good many independent analysts about what to expect from upcoming
chips. Our conclusions:
If price is your number one concern, buy a system that
uses AMD's K5, Cyrix's MediaGX or 6x86, or Intel's plain-vanilla
Pentium. AMD and Cyrix systems will probably be cheaper, but
Pentiums will be available in a wider selection of systems and
offer guaranteed compatibility.
For a home system you want to have fun with, get a Pentium
MMX. Prices are reasonable, and the newest games and multimedia
CD-ROMs will fly.
If you want speed but couldn't care less about multimedia,
consider a Pentium Pro, especially if you're running the latest
32-bit business software.
If you must have the latest, greatest technology--and are
willing to pay for it--check out Intel's Pentium II, Cyrix's M2,
and AMD's K6 MMX. As we go to press, we've tested one prototype
system with the K6, and another with the Pentium II; both
provided phenomenal performance.
Of course, the real test comes from running your own software on
shipping PCs. Before you buy, you need to know a little about
what's inside.
The CPU isn't the only factor that affects performance. A fast
hard drive and motherboard, along with an extra few megabytes of
system RAM, can speed up your PC to a startling degree. But you
can't base a truly fast machine on a slow processor. And what,
besides MMX support, makes a fast CPU?
Clock speed. It's no longer the criterion for judging CPU
performance, but clock speed still means a lot. Every time the
clock ticks (and in a 200-MHz CPU, it ticks 200 million times a
second), some little chore gets done. All else being equal, the
faster the clock ticks, the faster the chip finishes its work.
Cache memory. Inexpensive system RAM can't always feed a CPU the
data it needs quickly enough, and a bit of faster SRAM in between
the processor and the main memory improves things considerably.
This primary or level 1 cache is built into the CPU and runs at
the chip's own internal clock speed, which makes it as fast as
anything inside your computer. Intel and AMD split the primary
cache of their processors into two sections--for instructions and
data--allowing the CPU to quickly find each. In general, the
larger the primary cache, the faster the chip.
Systems typically help the CPU with a larger amount of their own
cache memory, called secondary or level 2 cache. In most cases,
this cache resides on the motherboard and runs at that board's
slower speed. To boost performance, the Pentium Pro comes with a
built-in secondary cache, while the Pentium II and future Intel
chips will put the cache in a package that bypasses the
motherboard.
Architecture. A microprocessor's architecture, or structure,
determines how it processes instructions and data. Modern CPUs
use one or more multistage pipelines to process more than one
instruction at a time. To keep a pipeline full and processing
efficiently, a CPU will guess what instructions to handle next.
If it guesses wrong, it must go back and perform the correct
operations. The better designed the CPU, the less often this will
happen.
Density. The tighter the transistors are packed, the faster the
chip. The CPU needs to synchronize signals traveling among
millions of transistors. Reducing the distance between
transistors allows the chip to run at higher speeds.
Most of today's processors space their transistors .35 micron
apart (a micron is about 1/100th the diameter of a human hair),
which effectively gives them a 200-MHz speed limit. Intel, AMD,
and Cyrix are all promising faster .25-micron chips by the end of
the year.
Tighter design also reduces the amount of silicon needed to
produce the chip, which helps keep manufacturing costs down
and--theoretically, at least--lowers the cost to consumers.
Which chip is best for you? Here's what we know and what we
predict about current and future CPUs.
We've limited the discussion here to x86 chips that can run DOS,
Windows 3.x, Windows 95, Windows NT, and OS/2. There are also
some high-end chips available that can run special versions of
NT. For a discussion of them, see "NT Spoken Here".
Available Now
Endangered species list included silicon-based life forms, the
original Pentium chip would be near the top. But this makes
Pentium systems an excellent choice for bargain hunters. At press
time complete Pentium PCs costing less than $1000 were just
starting to appear. If you're outfitting a small office, use
mostly business apps, and are trying to keep costs down, go with
a Pentium.
Intel says that it will continue to make Pentium chips as long as
there's a demand, and Pentium-based systems will probably be
available throughout 1997. After that? One PC vendor who wished
to remain anonymous told us, "Intel made it clear that by
the end of the year there would be no more non-MMX P-200s shipped
to us." Translation: Intel wants an MMX world.
AMD K5
When AMD's Pentium competitor first came out in March 1996, it
was almost a year late and performed slower than expected. But
AMD appears to have caught up. The one K5-PR166 system that the
PC World Test Center has tested, Polywell's Poly500Qx (no PR200
systems are yet available), was very impressive. It not only
outperformed most Pentium-166 systems--its score was just shy of
the average for similarly configured P-200s. (For details, see
Top of the News, April.) Pretty good for a low-price alternative.
AMD doesn't name a chip by its actual clock speed but by a rating
of equivalent Pentium performance (called a P-Rating or PR). For
instance, the K5-PR166 actually ticks away at 116.7 MHz. AMD will
be shipping the K5 throughout 1997 to Acer, Epson, Everex,
Monorail, and Polywell.
Cyrix MediaGX
This chip is good news if you need a basic computer for word
processing or Web browsing and can't see parting with $2000 or
more. The MediaGX puts SVGA graphics, Sound Blaster emulation,
and memory control on a single Pentium-compatible chip,
eliminating the need for a video card or sound board.
The first MediaGX PC we tested, the Compaq Presario 2100, lists
at $1298 with a monitor. But complete MediaGX systems may soon
sell for as little as $70o.
The trade-off is performance. The MediaGX, which will debut in
120- and 133-MHz versions, lacks a secondary cache and puts
greater demands on the CPU to handle video and sound. Despite its
133-MHz clock speed, the Presario 2100 performed about average
for a Pentium-100. Of course, the slower performance may be due
to reasons other than the CPU, and subsequent systems may turn
out to be faster. (For more on the Presario 2100, see New
Products, April.)
Cyrix 6x86
Pay a little less, get a little more. That describes the story of
the 6x86. Systems built around this chip are typically about 4
percent faster and $200 cheaper than otherwise equivalent
Pentium-based systems.
Compatibility can be an issue with non-Intel CPUs, and Cyrix's
chips have had slight problems in the past. Certain games, like
Activision's Mech Warrior 2, flash an error message on start-up
if they don't find an Intel chip. Most such messages can be
ignored, but some games require that you download a patch from
Cyrix's Web site (http://www.cyrix.com).
Like AMD, Cyrix labels the 6x86 not with its clock speed but with
a Pentium equivalent P-rating. The Cyrix 6x86-PR200+, for
example, has a clock speed of 150 MHz, but runs software slightly
quicker than the average Pentium-200.
Part of this gain comes from the 6x86's faster motherboard. A
200-MHz Pentium generally runs on a 66-MHz motherboard, slowing
down processing outside of the CPU. But 6x86-PR200+ systems use a
75-MHz motherboard, which allows data to move along a little more
speedily.
Until recently you could buy PCs directly from Cyrix; one such
system graced PC World's Top 20 Power Desktops chart for four
months. You can now buy 6x86 systems from CyberMax, Diamond, and
Kingdom, and from better-known companies like AST and IBM (which
makes its own 6x86 chips from Cyrix's design).
Intel Pentium MMX
Saddled with the official name "Pentium With MMX
Technology," Intel's latest chip offers more than just MMX.
There's a larger primary cache--bumped up from 16K to 32K--and
some minor architectural adjustments. These improvements give the
Pentium MMX consistently high scores on the PC WorldBench
benchmark, which doesn't even test MMX capabilities.
Is the Pentium MMX taking over? "I'd be surprised to see
non-MMX machines on the shelves past the end of this year,"
says Pathfinder's Thomsen. If you're on a tight budget and have
no interest in multimedia, you could save a little money by
buying a standard Pentium PC at a discount. Otherwise, a Pentium
MMX is an excellent first choice for most users.
Although Intel will neither confirm nor deny the rumor, Pentium
MMX-233 chips may be available by fall.
Intel Pentium Pro
A few months ago, the Pentium Pro was the ultimate CPU, despite
its unimpressive performance with 16-bit programs. Now eclipsed
by MMX models, the Pentium Pro is still the winner with 32-bit
code.
One reason the Pentium Pro is so fast is that the secondary cache
is built into the same package as the CPU and thus operates at
the chip's 166-to-200-MHz speed rather than the motherboard's
much slower 60 or 66 MHz.
Why does this lightning bolt turn into a lightning bug when
running old 16-bit software? To minimize the size of the chip,
Intel left out certain parts that the chip uses to speed up
16-bit code. If you use mainly 16-bit applications, you won't see
much benefit from the Pentium Pro.
Still, says Scott Miller of Dataquest in San Jose, California,
"the Pentium Pro addresses a viable market segment."
Its fast 32-bit performance makes the Pentium Pro today's chip of
choice for servers and high-end workstations. But for how long?
Look for the Pentium II to replace it in the long term.
Available Now
Endangered species list included silicon-based life forms, the
original Pentium chip would be near the top. But this makes
Pentium systems an excellent choice for bargain hunters. At press
time complete Pentium PCs costing less than $1000 were just
starting to appear. If you're outfitting a small office, use
mostly business apps, and are trying to keep costs down, go with
a Pentium.
Intel says that it will continue to make Pentium chips as long as
there's a demand, and Pentium-based systems will probably be
available throughout 1997. After that? One PC vendor who wished
to remain anonymous told us, "Intel made it clear that by
the end of the year there would be no more non-MMX P-200s shipped
to us." Translation: Intel wants an MMX world.
AMD K5
When AMD's Pentium competitor first came out in March 1996, it
was almost a year late and performed slower than expected. But
AMD appears to have caught up. The one K5-PR166 system that the
PC World Test Center has tested, Polywell's Poly500Qx (no PR200
systems are yet available), was very impressive. It not only
outperformed most Pentium-166 systems--its score was just shy of
the average for similarly configured P-200s. (For details, see
Top of the News, April.) Pretty good for a low-price alternative.
AMD doesn't name a chip by its actual clock speed but by a rating
of equivalent Pentium performance (called a P-Rating or PR). For
instance, the K5-PR166 actually ticks away at 116.7 MHz. AMD will
be shipping the K5 throughout 1997 to Acer, Epson, Everex,
Monorail, and Polywell.
Cyrix MediaGX
This chip is good news if you need a basic computer for word
processing or Web browsing and can't see parting with $2000 or
more. The MediaGX puts SVGA graphics, Sound Blaster emulation,
and memory control on a single Pentium-compatible chip,
eliminating the need for a video card or sound board.
The first MediaGX PC we tested, the Compaq Presario 2100, lists
at $1298 with a monitor. But complete MediaGX systems may soon
sell for as little as $70o.
The trade-off is performance. The MediaGX, which will debut in
120- and 133-MHz versions, lacks a secondary cache and puts
greater demands on the CPU to handle video and sound. Despite its
133-MHz clock speed, the Presario 2100 performed about average
for a Pentium-100. Of course, the slower performance may be due
to reasons other than the CPU, and subsequent systems may turn
out to be faster. (For more on the Presario 2100, see New
Products, April.)
Cyrix 6x86
Pay a little less, get a little more. That describes the story of
the 6x86. Systems built around this chip are typically about 4
percent faster and $200 cheaper than otherwise equivalent
Pentium-based systems.
Compatibility can be an issue with non-Intel CPUs, and Cyrix's
chips have had slight problems in the past. Certain games, like
Activision's Mech Warrior 2, flash an error message on start-up
if they don't find an Intel chip. Most such messages can be
ignored, but some games require that you download a patch from
Cyrix's Web site (http://www.cyrix.com).
Like AMD, Cyrix labels the 6x86 not with its clock speed but with
a Pentium equivalent P-rating. The Cyrix 6x86-PR200+, for
example, has a clock speed of 150 MHz, but runs software slightly
quicker than the average Pentium-200.
Part of this gain comes from the 6x86's faster motherboard. A
200-MHz Pentium generally runs on a 66-MHz motherboard, slowing
down processing outside of the CPU. But 6x86-PR200+ systems use a
75-MHz motherboard, which allows data to move along a little more
speedily.
Until recently you could buy PCs directly from Cyrix; one such
system graced PC World's Top 20 Power Desktops chart for four
months. You can now buy 6x86 systems from CyberMax, Diamond, and
Kingdom, and from better-known companies like AST and IBM (which
makes its own 6x86 chips from Cyrix's design).
Intel Pentium MMX
Saddled with the official name "Pentium With MMX
Technology," Intel's latest chip offers more than just MMX.
There's a larger primary cache--bumped up from 16K to 32K--and
some minor architectural adjustments. These improvements give the
Pentium MMX consistently high scores on the PC WorldBench
benchmark, which doesn't even test MMX capabilities.
Is the Pentium MMX taking over? "I'd be surprised to see
non-MMX machines on the shelves past the end of this year,"
says Pathfinder's Thomsen. If you're on a tight budget and have
no interest in multimedia, you could save a little money by
buying a standard Pentium PC at a discount. Otherwise, a Pentium
MMX is an excellent first choice for most users.
Although Intel will neither confirm nor deny the rumor, Pentium
MMX-233 chips may be available by fall.
Intel Pentium Pro
A few months ago, the Pentium Pro was the ultimate CPU, despite
its unimpressive performance with 16-bit programs. Now eclipsed
by MMX models, the Pentium Pro is still the winner with 32-bit
code.
One reason the Pentium Pro is so fast is that the secondary cache
is built into the same package as the CPU and thus operates at
the chip's 166-to-200-MHz speed rather than the motherboard's
much slower 60 or 66 MHz.
Why does this lightning bolt turn into a lightning bug when
running old 16-bit software? To minimize the size of the chip,
Intel left out certain parts that the chip uses to speed up
16-bit code. If you use mainly 16-bit applications, you won't see
much benefit from the Pentium Pro.
Still, says Scott Miller of Dataquest in San Jose, California,
"the Pentium Pro addresses a viable market segment."
Its fast 32-bit performance makes the Pentium Pro today's chip of
choice for servers and high-end workstations. But for how long?
Look for the Pentium II to replace it in the long term.
On the Horizon
Intel Deschutes available second half 1997 A smaller, faster
version of the Pentium II may hit the stores before the end of
this year. The Deschutes will use a new production process that
shrinks the space between transistors on the chip to .25 micron,
allowing for faster clock speeds.
Look for the Deschutes to push clock speeds up to 400 MHz, as
well as provide a few other design tweaks. Because of its small
size, the Deschutes may prove particularly popular in notebooks.
After Deschutes? There's talk of new Intel CPUs in the works with
picturesque code names like Katmai, Willamette, and Merced. But
the information we have about these chips--none of which Intel
will acknowledge--is still scant.
"New systems in 1996 were boring," points out
Dataquest's Brookwood. "We saw the same boxes with slightly
faster processors and much lower prices. Not so with 1997."
Nor, it appears, with 1998.
mnmn
PentiumIntelMar 93$1000-$2500100, 120, 133, 150, 166, 200none
N16YNow the lowest common denominator. A great bargain while it
lasts. K5AMDMar 96$900-$230075, 90, 100, 90/120 2, 100/133 2,
116/166 2133/200 2 N24YLate-coming, inexpensive alternative to
the Pentium. Fastest models not yet released. MediaGXCyrixFeb
97$700-$1300120, 133150, 166, 180, 200N 316NAll-in-one chip
designed for inexpensive systems. For bargain hunters.
6x86CyrixOct 95$800-$2500100/120 2, 110/133 2, 120/150 2, 133/166
2, 150/200 2none N16NA fast, inexpensive Pentium competitor.
Pentium MMXIntelJan 97$1600-$2800150, 166, 200233 Y32YThe first
chip with MMX technology, it is Intel's replacement for the
Pentium as most popular chip.
Currently the fastest chip overall. Pentium ProIntelNov
95$1500-$4000166, 180, 200none N16YHigh-end, non-MMX chip is very
fast with 32-bit code, unimpressive with 16-bit.
Best choice for servers and power users only. Coming Soon
Pentium IIIntelexpected Q2 97$3000-$5000n/a 233, 266, 300Y32YMMX
successor to the Pentium Pro promises better 16-bit performance,
multimedia support. K6 MMXAMDexpected Q2 97$2500-$4500n/a 200/233
2, 266/300 2Y32YAMD's MMX chip may prove faster and less
expensive than the Pentium II. M2 4Cyrixexpected Q2
97$3500-$4500n/a 180, 200, 225, 233Y64NCyrix's answer to the
Pentium II may also be a fast yet inexpensive competitor. On The
Horizon
Deschutes4Intelexpected late 97unknownn/a300, 333,
400YunknownunknownLittle is known about this smaller, faster
version of the Pentium II,
but it's expected to reach speeds of up to 400 MHz. 1 Separate
instruction and data caches. 2 Actual clock speed/equivalent
Pentium speed. 3 200-MHz version will support MMX. 4 Code name.
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