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Publisher4.4 Choosing a Processor
The
processor you choose determines how fast the system runs, and how
long it will provide subjectively adequate performance before you
need to replace the processor or the system itself. Buying a
processor just fast enough to meet current needs means that
you'll have to upgrade in a few months. But
processor pricing has a built-in law of diminishing returns. Spending
twice as much on a processor doesn't buy twice the
performance. In fact, you'll be lucky to get 25%
more performance for twice the money. So although
it's a mistake to buy too slow a processor,
it's also a mistake to buy one
that's too fast. Consider the following issues when
choosing a
processor:
What kind of applications do you run and how long do you want the
system to be usable without requiring an upgrade? If you run mostly
standard productivity applications and don't upgrade
them frequently, a low-end processor may still be fast enough a year
or more after you buy it. If you run cutting-edge games or other
demanding applications, buy a midrange or faster processor initially,
and expect to replace it every six months to a year. But expect to
pay a price for remaining on the bleeding edge.
Do you mind upgrading your system frequently? If you
don't mind replacing the processor every six to 12
months, you can get most of the performance of a high-end system at
minimal cost by replacing the processor frequently with the
then-current midrange processor. In the past, this was easier with
AMD processors because AMD has used Socket A for years and had
standardized on 100/200 MHz and 133/266 MHz FSBs. It was sometimes
possible to install a current processor in a two-year-old motherboard
with only a BIOS upgrade.Intel made things much more difficult, replacing Socket 370 with
Socket 423 and then Socket 478, and introducing faster FSB speeds
frequently. Although many considered these changes as cynical planned
obsolescence, in fact these changes resulted simply from
Intel's much faster product development cycle. The
situation is different now. Intel has stabilized around Socket 478
and the 800 MHz FSB (although the forthcoming Prescott processors
will use a different socket), and AMD is in a state of flux. AMD
recently introduced the 166/333 MHz and 200/400 MHz FSBs for the
Athlon, which will rapidly render older motherboards obsolete. Also,
AMD has deemphasized Athlon product development in favor of its
forthcoming Hammer-series processors, which are entirely incompatible
with the Athlon series. On balance, Intel actually offers a better
upgrade path for now, although that may change depending on the
decisions AMD makes with regard to Hammer-series processors.
If you're working on a fixed budget,
don't spend too much on the processor to the
detriment of the rest of the system. Instead of spending $300 on a
fast processor and compromise on the other components,
you're better off spending $150 on a midrange
processor and using the other $150 to buy more memory, a faster hard
disk, and better video. A low-end Pentium 4 with lots of memory, a
fast hard drive, and a good video adapter blows the doors off the
fastest Pentium 4 with inadequate memory, a slow hard drive, and a
cheesy video card every day of the week. Don't make
yourself "processor- poor."
Keep
form factor in mind when you're shopping for a
processor, particularly if you're also buying a
motherboard:
Don't consider buying a Socket 7 processor, even as
an inexpensive upgrade to a working system. Any money spent on Socket
7 is wasted. Retire the old system to less-demanding duties, and
build or buy a new system instead.
Slot 1 was obsolete by the end of 2001. Although new Slot 1
processors remain in limited distribution, new Slot 1 motherboards
are now almost impossible to find. An existing Slot 1 system may or
may not be a good upgrade candidate depending on the motherboard
characteristics. Some Slot 1 motherboards support fast Pentium III
processors, and can be upgraded at reasonable expense. For example,
we recently upgraded an older Pentium II server to a Pentium III
using a salvaged processor. Because we used a relatively slow Pentium
III processor, even if we had to buy the processor, the total upgrade
cost would have been about $75. Performance more than doubled, which
gives that server another two years or more of useful life.Other Slot 1 motherboards have neither BIOS support nor adequate VRMs
to support faster processors. Although it's possible
to upgrade those systems with marginally faster Slot 1 processors,
doing so makes no economic sense. Before you upgrade any Slot 1
system, check prices carefully. Some Slot 1 processors are very
expensive relative to the performance boost they provide. You may be
able to replace the motherboard, processor, and
memory with Socket 478 Pentium 4 or Socket A Athlon components for
little more than the cost of the Slot 1 processor alone.
Like Intel processors, AMD Athlon processors were originally produced
in slotted versions, which were subsequently replaced by socketed
versions. Slot A motherboards and processors are now almost
impossible to find, and any Slot A motherboard is now so old that it
is a poor upgrade candidate. If for some reason you must replace the
processor in a Slot A system, pay careful attention to the chipset it
uses. Motherboards based on the AMD-750 chipset can use Slot A
processors based on the K7, K75, and Thunderbird cores (although Slot
A Thunderbirds are difficult to find). Motherboards based on the VIA
KX133 chipset are incompatible with Slot A Thunderbird Athlon
processors, but can use Athlons based on the K7 and K75 cores. As of
July 2003, Slot A processors are still in limited distribution, but
soon the only alternative will be the used market.
As of July 2003 Socket 370 is moribund. Intel pulled out all the
stops to push the Pentium 4 at the expense of its sixth-generation
Celeron and Pentium III processors, and by mid-2002 Socket 370 was no
longer a mainstream technology. Intel still offers a limited
selection of Socket 370 Celeron and Pentium III processors. Alas,
Intel no longer makes Socket 370 motherboards, so third-party
motherboard makers are now the only source for new Socket 370
motherboards.Although it no longer makes economic sense to build a new Socket 370
system, existing Socket 370 systems may be economically upgradeable.
When upgrading an older Socket 370 system, verify compatibility
between your motherboard and the Socket 370 processor you propose to
buy. There are many incompatibilities between older motherboards and
newer processors. Some problems can be solved with a simple BIOS
update, but many are unsolvable because the older
motherboard's chipset or VRMs do not support newer
Socket 370 processors.
In the past, AMD did a much better job than Intel at maintaining
backward compatibility. Intel changed sockets and FSB speeds
frequently, but AMD just kept using Socket A and the standard 100/200
and 133/266 MHz FSB speeds. The Hammer-series processors, due later
in 2003, will change that, but Socket A motherboards and processors
will remain available for at least the next year or two. As long as
you don't mind buying into an obsolescent
technology, Socket A remains a good choice for a new system until
Hammer-series processors and motherboards become inexpensive
mainstream products.Older Socket A systems may or may not be good upgrade candidates. In
general, older-model Socket A motherboards can use newer Socket A
processors, although perhaps not the fastest models. A Socket A
system that supports only the 200 MHz FSB is probably too old to be
economically upgradeable. For such systems, replace the motherboard,
processor, and memory with current products. Most Socket A systems
that support the 266 MHz FSB or higher and that support at least
PC2100 DDR-SDRAM are excellent upgrade candidates. By replacing an
older Duron or Athlon processor with a current low-end Athlon, you
may be able to double system performance for much less than $100.
Before you make such an upgrade, verify that your motherboard
supports the specific processor model and speed that you plan to
install. You will probably need to upgrade the BIOS as well.If your goal is to build a dual-processor system, your best option is
a pair of Socket A Athlon MP processors running in an AMD-760MPX
based motherboard. As always, an older motherboard may have BIOS or
VRM issues with newer processors, so you still need to verify
compatibility.
Socket 423 was Intel's first socket for the Pentium
4, and was simply a stopgap solution that allowed Intel to bring
Pentium 4 processors to market quickly to compete with the AMD Athlon
on clock speed. Socket 423 processors and motherboards are obsolete.
Socket 423 motherboards are nearly impossible to find, although
Socket 423 processors remain in limited distribution. A Socket 423
system is a poor upgrade candidate because the fastest available
Socket 423 processor will be little or no faster than the processor
already installed. Replacing the motherboard, processor, and memory
is a far better solution.
A Socket 478 processor is the best choice if you are building a new
mainstream system. An existing Socket 478 system can easily be
upgraded simply by dropping in a faster Socket 478 processor, a
condition that is likely to remain true for some time. As always,
it's possible that BIOS, chipset, and VRM issues may
restrict the speed of the fastest Socket 478 processor that can be
installed in a particular motherboard, but Socket 478 currently
offers the best options for future upgradability.
When upgrading a system, the existing motherboard determines
upgradability, as follows:
These motherboards are simply too old to upgrade economically. We
recommend retiring such ancient systems, or discarding them entirely.
Slot 1 Pentium II and Celeron processors remain in limited
distribution, although we expect them to disappear entirely by the
end of 2003 or early 2004. Fortunately, some Slot 1 motherboards can
be upgraded by using a slocket adapter, which accepts a Socket 370
processor and plugs into the motherboard Slot 1. The best candidates
for such upgrades are motherboards designed for the Pentium III that
support the 100 MHz or 133 MHz FSB. Even if a particular motherboard
can be upgraded via slocket, it may be limited by BIOS, chipset, or
VRM issues as to which particular Socket 370 processors are usable.
In general, FC-PGA Celerons are the most likely to work, assuming
that the motherboard supports the Celeron L2 caching method. An
FC-PGA Coppermine-core Pentium III may or may not work, depending on
the particular slocket/processor combination and the chipset and BIOS
configuration of the motherboard. We know of no slocket that allows
FC-PGA2 Celerons and Pentium IIIs to be used in Slot 1 motherboards.
Before you attempt to upgrade a Slot 1 motherboard with a slocket,
verify with the slocket maker that the slocket, processor, and
motherboard you plan to use are compatible.
Slot A processors are now almost impossible to find new. Slot A
motherboards are now so old that it makes no sense to spend money
upgrading them. Instead, replace the processor, motherboard, and
memory with current products. You can buy a decent Socket A
processor, motherboard, and memory for less than
$200, which makes messing around with an obsolete processor and
motherboard a complete waste of time.
Upgrading a Socket 370 system should be easy.
Unfortunately, it often isn't. The problem with
upgrading Socket 370 motherboards is that there have been so many
variants of the socket itself and processors intended to fit it that
determining compatibility can be difficult. Any Socket 370 processor
physically fits any Socket 370 socket, but there are actual pinout
differences between early Socket 370 sockets and processors and later
versions. Late-model Socket 370 processorsCoppermine- and
Tualatin-core Celerons and Pentium IIIswill not operate in
early-model Socket 370 motherboards, and early-model Socket 370
processorsMendocino-core Celerons and Katmai-core Pentium
IIIsmay or may not operate in later-model Socket 370
motherboards. In addition, chipset issues are important with Socket
370 because early Socket 370 chipset revisions do not support later
Socket 370 processors, even though the processor is otherwise
compatible electrically and physically with the socket. Intel
rationalized this situation in late 2001 by introducing its so-called
"Universal" Socket 370
motherboards, which can accept any Socket 370 processor. If you
intend to upgrade the processor in a Socket 370 system, the best
advice is first to determine exactly what motherboard you have
(including revision level). Once you've done that,
visit the motherboard maker's web site and read the
technical documentation to determine which currently available Socket
370 processors can be used in that motherboard.
Motherboards that use any of these sockets can be upgraded using
current processors. Socket 423 is a poor upgrade candidate because
only relatively slow processors are available for it. Socket A and
Socket 478 motherboards are generally good upgrade candidates because
there are numerous models of fast, inexpensive processors available
for both of them. As always, check the documentation for the
motherboard to ensure that it supports the type, FSB speed, and clock
speed of the processor you plan to install. Ordinarily, such upgrades
are relatively straightforward, requiring a BIOS upgrade at
most.
