P4 Readiness and Installation
by Kenny Bellew
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If you are pondering an upgrade from a non-Pentium 4
processor to a Pentium 4, you may be in for a few surprises. New
requirements, specifications and compatibility issues are going to force you to
examine the power supply, case (the chassis), memory, motherboard, video card
and, perhaps, even the operating system.
The following article will assist you in preparing for and performing an
upgrade to a Pentium 4 based system.
- 423-pin (socket 423) or 478-pin (socket 478)
- Motherboard Requirements
- Memory Requirements
- Pentium 4 Case Requirements
- Power Requirements
- Video Requirements
- Operating System Requirements
- Pentium 4 Readiness Checklist
- Installing the 478-Pin Pentium 4 CPU
P4 form factors: 423-pin (socket 423) or 478-pin (socket
The Pentium 4 processor for the desktop PC comes in two
configurations: 423-pin and 478-pin. The 478-pin processor, with its additional
55 pins, is actually the smaller of the two (see Figure 1). Pentium 4 processors
below the 2 GHz level can be either a socket 423 or a socket 478. At equal
processor speeds 2 GHz, there is no direct performance advantage to either
configuration when comparing the original 256k cache P4 units. When comparing
the 512k cache 478 pin processor of the same speed to the 423 unit the 478-pin
Fig. 1. 423-pin on left and 478-pin on
The 478-pin processor is now the preferred type as Intel has discontinued the
Socket 423 standard.
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Motherboards supporting Pentium 4 are available in two
standard form factors: ATX and MicroATX. When purchasing a Pentium 4 motherboard
it is important to check and make sure that the motherboard supports the
processor you are going to use (Socket 423 for 423-pin processors or Socket 478
for 478-pin processors) as well as the bus speed of the processor itself (either
400MHz or 533Mhz). Above the 2 GHz level, the Pentium 4 is only
available in socket 478. If your plan is to begin with a low-end Pentium 4
processor and upgrade later, make sure that you purchase a 478-pin processor and
Fig. 2. 478-pin ATX motherboard on left
and 478-pin MicroATX on right
If you want your system to support the latest Pentium 4
processors such as the latest 3.06 GHz processor, a well-thought-out plan is
needed. Specifically, you must select a motherboard that supports both
478-pin processors and Hyper-Threading. Read the motherboard
specifications closely, especially if you have chosen a motherboard with a
non-Intel chipset. For example, just because the motherboard is socket 478 and
sports a chipset with 533 MHz Front Side Bus (FSB), does not mean that it
Note: Front Side Bus speed refers to the speed that the CPU can
exchange data with the RAM and other system components. Motherboards with
Pentium 4 chipsets support either 400 MHz FSB or both 400 MHz/533 MHz FSB.
All motherboards with an Intel chipset that support the 533 MHz FSB also
support Hyper-Threading. However, this is not true for some non-Intel chipsets.
For example, the popular Pentium 4 motherboard from Soyo, the P4X400
Dragon Ultra Platinum, uses the VIA P4X400 chipset. The VIA P4X400 chipset
supports 533 MHz FSB and DDR400 RAM and even AGP 8X; however, it does not
Update: Soyo recently released a bios update that solved the problem. The P4X400 does support HT after a update. For other boards please consult the website of the manufacturer. Many manufacturers are releasing bios updates that support HT. PCB revision may play a factor though so proceed with caution when purchasing / upgrading older boards.
If you are considering upgrading from an early model 423-pin
Pentium 4 to a faster 478-pin Pentium 4, you should plan on buying a new socket
478 motherboard. There are converters on the market that will allow a
socket 423 motherboard to use a 478-pin processor. However, for slightly more
then the price of a converter, a socket 478 motherboard can be purchased. Intel
moved to the 478-pin processor in order to achieve better stability at higher
processor frequencies. Stability issues surrounding the use of a
423-pin-to-478-pin converter have not been widely discussed. If you decide to
use a converter, you will need to fully understand chipset compatibility issues
(or lack thereof) before installing a 423-pin-to-478-pin converter.
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If you are upgrading from a non-Pentium 4 processor, you may be using SDRAM,
such as PC 133. If you are planning on using some components from an older PC in
your Pentium 4 PC, it is natural to consider using your existing SDRAM in your
new Pentium 4. This is possible, but it is not recommended. Mixing the old
technology with the power of the Pentium 4 will bottleneck the potential gains
you may be trying to achieve. Nonetheless, there are motherboards that support
this. Some motherboards will even provide two slots for SDRAM and two different
slots for DDRAM; however, you cannot install both at the same time. You must
choose one or the other.
Fig. 3. SDRAM - top, DDR - middle and Rambus
There are three categories of RAM that can be installed into a Pentium 4
motherboard: SDRAM, DDR (Double Data Rate) and Rambus, also known as a RIMM.
While a thorough explanation of the differences in RAM is beyond the scope of
this article, generally speaking, DDR and Rambus move information faster and at
a greater bandwidth than standard SDRAM. You will need to decide on your memory
type before choosing your motherboard. Each type of memory is keyed differently
(see Figure 3), so, for example, you cannot insert a stick of DDR into a slot
that was meant for Rambus or SDRAM. Each type of RAM slot will prevent you from
inserting the wrong RAM type.
As you prepare to upgrade to Pentium 4, study the current and projected
differences between DDR and Rambus. Once you decide you like the features of one
over the other, you will need to find a motherboard that supports your processor
pin type (423 or 478-pin) and that particular type of RAM. Once you understand
the type of RAM the motherboard supports, you need to understand the highest
speed rating (or frequency) of the RAM that you can install in the
motherboard. The RAM's bandwidth and speed are directly linked to the
Front Side Bus speed.
Before you buy RAM for your new motherboard, be sure to understand the
highest RAM speed rating the motherboard can accept. Generally, the
faster the speed rating of the RAM, the more it will cost. You could easily
purchase RAM that was rated for speeds higher than your motherboard can
support. Such RAM will probably work in your motherboard, but the speed
potential will never be realized. Motherboard advertisements will normally list
the supported RAM and RAM speeds to help you plan accordingly.
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Pentium 4 Case Requirements
What does it mean for a case (or chassis) to be Pentium 4
compatible? There are a couple of important requirements that the Pentium
4 chassis must meet. One requirement only applies to socket 423 motherboards. In
order to support the gargantuan heatsink and fan needed
for the 423-pin Pentium 4, four additional holes are needed in the chassis for
the mounting standoffs. These four standoffs support the motherboard under each
corner of the CPU socket. A few motherboard manufacturers include a metal plate
that is the size of the socket 423 motherboard. The metal plate acts as an
adapter, allowing you to bolt the plate to the traditional ATX standoff
locations, and then bolt the motherboard to the metal plate. However, many
recently manufactured cases include these four standoff holes in the chassis.
You will need to investigate whether or not a chassis you are considering has
Fig. 4. Case with additional airflow fans and
The remaining Pentium 4 case specifications are mainly about
airflow. The Pentium 4 chassis requires a minimum of one, 80mm chassis fan - in
addition to the fan in the power supply, and enough ventilation to maintain
adequate airflow around the processor.
Note: If the case contains a power supply, there are
specific Pentium 4 requirements for the power supply that will be discussed
The newest generation of Pentium 4 processors has raised the
bar for cooling requirements. Unless you are planning for non-traditional
cooling methods, such as liquid cooling, the airflow capabilities of the case
must be considered. The amount of airflow that is needed is determined by
several factors such as the ambient air temperature, number of internal devices,
(hard drives, video card, CD-ROM, etc) efficiency of the power supply as well as
its ability to remove heat. Depending on these variables, a Pentium 4 ready case
is likely to require additional airflow fans - both to suck air in and to blow
One way to determine if additional airflow into and out of the case is
necessary is to measure the air temperature within the case. If
you are using the stock heatsink and variable-speed fan that came with the boxed
processor (versus an OEM version) or an off-the-shelf heatsink fan that is
thermostatically controlled, you will notice that as the air temperature inside
the case increases, so does the fan speed (and noise level). Pentium 4
socket-478 processors 2.8 GHz and below require that the internal case
temperature not exceed 40oC (104oFahrenheit). Pentium 4 socket-478 processors that are 3.06 GHz and
above require that air temperature does not exceed 38oC (100.4oFahrenheit). The socket-423
Pentium 4's maximum air temperature is 45oC (113o
Fahrenheit). At higher air temperatures, the heatsink
fan (HSF) will be operating at maximum speed and cease to provide adequate
cooling. Therefore, a case that is P4 compatible must provide adequate airflow
to maintain these increasingly stringent cooling requirements.
The Pentium 4 CPU has the built-in ability to monitor its own
temperature. One of the things that the Pentium 4 CPU will do to avoid
heat-related damage is to slow the processing speed down when temperatures get
too hot. If temperatures get dangerously hot, it will shut down
Ideally, a Pentium 4 case will have adequate ventilation to
keep the air temperature (inside the case) cool enough to maintain the fan at
its lowest speed when the CPU is idle. While not all variable speed
heatsink fans (HSF) have the same temperature set points (temperature at which
the fan speed changes), there is a general rule of thumb. Generally, a variable
speed HSF should be able to maintain adequate cooling for the CPU at its lowest
fan speed while the air temperature is 33oC
(91.4oFahrenheit) or lower within the case. If the
Pentium 4 is 3.06 GHz or higher, the specifications are only slightly lower at
32oC (89.6oFahrenheit). Information on chassis and temperature
specifications can be found on Intel's website linked here.
As many Pentium-4-ready cases come with additional fans,
consider an at-a-glance temperature monitoring device that also allows the
manual control of case fan speed (see Figure 5). For example, there may be times
when you require a lower noise level. At-a-glance temperature monitoring will
allow you to lower the fan speed manually, while providing the peace of mind
that your Pentium 4 CPU is still within its cooling specification. This is
especially useful for front intake fans. Fans that suck in outside air are
less instrumental at cooling the case than rear fans that blow out warm air. If
you have adequate chassis ventilation, you may opt to lower the front fan speed
when you need a quieter environment.
Fig. 5. At-a-glance temperature display, fan-speed
control with USB and firewire
Unfortunately, once you obtain a case that meets the Pentium
4 specifications, you can easily and quickly disqualify it. Standard ribbon
style IDE and floppy cables can easily block airflow if they are not carefully
managed, there by making your case no longer meet Pentium 4 case specifications.
To help prevent this, use rounded IDE and floppy cables. Tuck all power cables
neatly into wire looms, routing them along the contours of the case. Cables not
only block airflow, but they trap heat. This could create hotspots that even an
at-a-glance air temperature gauge will not detect.
To summarize Pentium 4 case requirements, look for a case
that includes multiple case fans and is large enough or vented enough to promote
proper airflow. A larger case will also allow you to route cables in such a way
that airflow to and from the processor is not blocked.
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Fig. 6. The 4-pin 12V ATX12V cable that connects from
the power supply to the motherboard
The Pentium 4 requires a specific type of power supply. In February of 2000,
the public version of the ATX / ATX12V Power Supply Design Guide Version 1.0 was
released. This changed the specifications for ATX power supplies. One of
the most important changes was the addition of a 2x2 4-pin 12V output connection
that plugs directly into the motherboard (see Figure 6). This additional 12V
connection classifies the ATX power supply as "ATX12V." An ATX12V power
supply is required for all Pentium 4 desktop configuration and even some newer
AMD Athlon XP configurations. The 4-pin 2x2 12V cable was also added to the
MicroATX specification, giving it the nomenclature of "SFX12V". The ATX12V and
SFX12V also received an increase in the specifications for 3.3V and 5V
The Pentium 4 motherboard requires this additional 2x2 4-pin 12V cable in
order to provide the additional current needed for the Pentium 4 CPU. The
4 pins consist of two yellow wires that carry 12V current and two black ground
wires. Before Pentium 4 and ATX12V, the motherboard's power connection had
only one wire providing 12V current to the entire motherboard. This one wire was
able to provide about 5 Amps, which is 60W of power (12V x 5 Amps = 60
Watts). The Intel website points out that the Pentium 4 processor alone is
able to draw this much power.
Note 1: An ATX12V power supply / P4 ready power supply will work properly with motherboards that do not need the 2x2 12V connection. This means that it is fine to use a P4 ready power supply with a motherboard intended for other types of processors such as those made by AMD or VIA. These types of power supplies are also fine for older Intel motherboards for Pentium III and below.
Note 2: Many Asus P4 motherboards can take a standard 4-pin power plug
instead of a 2x2 4-pin connector without using an adapter.
If you have a power supply that does not have the 2x2 4-pin connector, resist
the urge to use it with your Pentium 4. To do so is to invite disaster.
There is an adapter available that will convert a single 12V molex connector
into the 2x2 4-pin 12V connector. However, by using the adapter, you allow
current that was intended to flow through two wires (the two yellow wires in the
2X2 4-pin cable) to flow through only one wire (the yellow 12V wire in the molex
cable). This will cause more current to flow through the wire than was intended.
This can cause failure of system components and power supply and general
main power to motherboard
Fig. 7. Various cables from ATX12V power
How many Watts of power do you need with Pentium 4? It depends on your
configuration. Intel states that the absolute minimum is 250W total power. Keep
in mind that the power supply's capacity to deliver power is divided by the
various voltage rails, mainly: 3.3V, 5V and 12V. Not all power supplies are the
same in the way the this power is distributed. One power supply may only
be able to maintain 10 Amps at 12V, while another might be rated to maintain 16
Amps of 12V current. Generally, as the total power rating of the power supply
increases, the total Amps available to each of the various voltages also
increases. However, this is not always true. At a minimum, look for a power
supply that can deliver a continuous output of 26 Amps at 3.3V, 30 Amps at 5V
and 15 Amps at 12V.
In order to determine the total Watts you need for your Pentium 4, you need
to examine current and future plans for the PC. If all you plan on doing
is surfing the web, processing text and sending email, you can probably get by
with a 300W power supply. On the other hand, do you plan on doing any of the
following: overclock, use high-powered video cards (AGP50 can use 50W), have
multiple hard disks, DVD/R, CDR drives, fans, cathode lighting, PCI cards? If
so, a 400W power supply is reasonable for the power user. Unless you have
unusual power requirements, such as stacked drive arrays, it is unlikely current
Pentium 4 configurations will need power supplies in the 500W range. However,
that doesn't mean that you should not consider a 500W power supply.
Before you decide on the wattage of the power supply, keep the following in
mind. Power supplies have a rating called "efficiency". The
specification for ATX12V is that the power supply be at least 68%
efficient. This means that the power supply must be able to convert at
least 68% of the AC current coming into the power supply into DC current. What
happens to the remaining 32%? It turns into heat that the power supply
must remove from the PC.
This makes for a couple of interesting points. Just because a power supply is
rated at 400W or 500W does not mean that it will use more AC current than a 300W
power supply. It will only use what it needs. However, the 500W power supply
must be better at removing heat than the 300W power supply. The size of the
power supply does not change, regardless of wattage; however, the 500W power
supply must be prepared for dealing with a lot more heat than the 300W power
supply. Because the power supply box size limits the size of its heatsink,
the only other way it has to deal with heat is to increase the quality of the
heatsink and by increased airflow. Ideally, the higher wattage power
supplies will have high quality heatsinks and multiple
thermostatically controlled fans. This translates to a cooler power supply,
a cooler CPU and reduced noise. On the other hand, more than a few
high-wattage power supplies have been known to have poor fan speed management.
The noise level of high-dollar power supplies can be either disappointing or
impressive. Ultimately if you are going to purchase a high wattage power supply
it is best to research the model you are interested in through various hardware
enthusiast review web sites and magazines.
To summarize power supply requirements for the Pentium 4, make sure that the
power supply is ATX12V and is able to handle cooling without sounding like a
helicopter. A 400W power supply is recommended for the average power user, while
the web-surfing-only PC can probably get by with a 300W power supply just fine.
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Fig. 8. AGP slot (brown) keyed for 1.5V. The spacer
(covered with the red tag) is removed for AGP Pro cards
Do you need a new video card in order to upgrade to Pentium 4? Of
course, it depends on what your current video card is. If you are using an
old-style PCI video card, and you are pleased with its performance, you can use
the same PCI video card with your Pentium 4 motherboard. However, for most
upgraders, the burning questions is whether or not his or her current AGP
(Advanced Graphics Port) video card will work with the Pentium 4
When AGP cards were introduced in 1996, the signaling voltage was 3.3V. As
AGP video cards advanced, the signaling voltage reduced to 1.5V and to
0.8V. The "speed" of the video card/AGP slot began to be identified by the
amount of data that could be provided to the video card. As the amount of data
doubled, the speed rating doubled. Therefore, AGP cards began to be
identified as AGP 1X, AGP 2X, AGP 4X and, AGP 8X.
Currently, the majority of Pentium 4 motherboards support AGP 4X at
1.5V. Most Pentium 4 AGP slots only allow 1.5V video cards (4X and 8X).
Some, called Universal AGP, allow both 3.3V and 1.5V (AGP 2X, 4X, and 8X).
Generally speaking, AGP is backwards compatible for speed but not necessarily
for voltage signaling. You should be able to use any previous AGP video
card in a new Pentium 4 motherboard, with the exception of the original 1X and
2X 3.3V cards (which could damage the motherboard if installed). For more
information on this topic please see our guide.
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Operating System Requirements
The only notable Pentium 4 operating system requirement relates to
Hyper-Threading. Pentium 4 CPU's with Hyper-Threading capabilities can
process two threads from the operating system at the same time. However,
the operating system and the 3rd-party software installed must be able to
separate the requested processes into dual threads. Operating systems that
support dual processors, such as Windows NT, Windows 2000 and Linux, have been
doing this for some time now. However, currently, only Windows XP
Professional Edition, Windows XP Home Edition and Lynux (with a Hyper-Threading
optimized Lynux kernel) support the Pentium 4 Hyper-Threading.
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Installing the 478-Pin Pentium 4 CPU
Fig. 9. Boxed heatsink fan and 478-pin Pentium 4
1. Take precautions to control static electricity.
Before beginning, make sure you are able to take proper steps to control
static electricity. Working on delicate electronics without proper static
control is like a doctor performing surgery without washing his hands. Damage
may not be immediate, but latent effects could cause premature component death.
A properly grounded wrist strap used correctly should be the minimum static
|Fig. 10. Static-control
wrist strap and motherboard placed on a static resistant mat that is
grounded to the earth ground of an electrical outlet
||Fig. 11. Bent pin that
needs to be straightened |
2. Examine all 478 pins, making sure none are bent or damaged.
Once proper static control is established, remove the Pentium 4 processor
from its packaging and examine the pins. Look for bent or damaged pins (see
Figure 11). It is unlikely that a new processor will have bent pins;
however, if bent pins are found, they must be straightened before the processor
can be installed. Break a toothpick in half and use the blunt end of the
toothpick to move the pin from its bent position to vertical (slowly and
3. Open the socket handle on the motherboard.
The socket handle is held in place by a small plastic tab (see point B in
Figure 13). Gently push the socket handle in the opposite direction from the tab
until it clears the retaining tab. Lift the socket handle into a vertical
Orientation indicator in corner of 478-pin Pentium 4 CPU
A. Alignment corner for orientation indicator
Socket handle retainer
C. Socket handle
Aligning processor with socket
4. Locate the triangular orientation indicator on the pin side of the
In one of the corners of the pin-side of the processor, is a light-colored
triangle (see Figure 12). There is one pin missing at the end of each of the two
rows of pins closest to the triangle. This triangle is the
5. Align the orientation indicator with the corresponding socket corner
(see Figure 13), and install the processor into the socket.
Once the processor is oriented properly, align the pins of the processor with
the socket, and allow the processor to drop into place. With all pins inserted,
the processor should be level. If the processors appears to be lifted
slightly at one corner, check to make sure that the processor is properly
oriented (see Figure 13).
With the pins inserted into the socket, press gently on the center and then
the four corners of the processor to ensure proper seating of all pins.
6. Return the socket handle to its latched position (see Figure 15).
|Fig. 15. Socket handle is
||Fig. 16. Isopropyl
7. Make sure the top of the processor and bottom of the heatsink are
Before installing the heatsink fan (HSF), clean the top of the processor with
a lint-free cloth that has been lightly moistened with 70% isopropyl alcohol
(common rubbing alcohol - see Figure 16). This will remove finger oils and
prepare the processor to receive the thermal compound.
8. If using a non-boxed-processor HSF, apply a thin layer of thermal
compound to the top of the processor.
NOTE: The bottom of the HSF that ships with the
boxed Pentium 4 comes with a thermal phase change pad installed. If you wish to
use a more effective thermal interface such as Arctic Silver thermal compound
then you will need to first remove the pad from the heatsink. The pad is most
easily removed by using a combination of isopropyl alcohol and a flat dull
object such as a old credit card. Be careful not to scratch the bottom of the
heatsink too badly when removing the pad as this will decrease the thermal
Follow the directions supplied by the manufacture of the thermal compound you
are using to apply a thin layer of the thermal compound to the top of the CPU.
Avoid getting the thermal compound on any circuit board traces. Make sure the
thermal compound only contacts the metal top portion of the processor. Do not
apply compound if you intend to use the thermal phase change pad that comes with
the retail box heatsink. Using the pad and thermal compound together is worse
then using either one alone.
9. Plug in the power cable for the HSF to the motherboard (see Figure
You can perform this step at any time. However, the power connection location
on some motherboards is very close to the edge of the HSF, making it more
difficult to access after the fan is installed. If this is not the case for your
motherboard, wait until after the HSF is installed to plug in the power
10. Place the heatsink fan on top of the Pentium 4 CPU, aligning each of
the four retention clips with their corresponding retention bracket slots (see
Be sure not to twist the HSF as you place it on top of the CPU. Do not slide
the HSF around on top of the processor. Try not to disturb the thermal compound
that was applied to the top of the CPU.
Note: If you plan on installing a temperature monitoring device, such
as the one in Figure 5, the temperature sensor will be installed between the
edge of the heatsink and the CPU (but not touching the CPU die). Plan ahead to
have the temperature monitoring device before you install the processor. You
want to avoid having to remove the heatsink once it has been installed.
11. Press at each corner of the HSF to lock each of the four retention
clips into the retention bracket.
12. Move the clip levers that are on top of the HSF into the closed
position (see Figure 23 and 24).
|Fig. 23. Locking clip levers into place
||Fig. 24. HSF clips
Installation of the Pentium 4 processor is now
The above information has been provided as a reference only. Directron.com is not responsible for any damage or problem caused as a result of correctly or incorrectly following the instructions outlined therein.
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Related Articles: | Understanding System Memory and CPU speeds: A layman's guide to the Front Side Bus (FSB) |
Last Updated: Jan 12th, 2003
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