Intel Xeon Overclocking
Intel Xeon Overclocking
Intel Xeon Overclocking
Platform
By # , MAY 14, 2004 11:00 AM
W hen w e compare, for example, the price of a Pentium 4 Extreme 3.2 GHz against two Xeons with 2.8 GHz,
w e see that the latter option turns out to be much less expensive. A Pentium 4 Extreme costs $950, w hile tw o
2.8 GHz Xeons can be had for $760. Applications that explicitly support the dual processor environments
usually operate much faster with two CPUs than with one.
Also, a lot has happened in the area of memory technology. Thanks to the introduction of the AMD Athlon FX,
Registered DDR memory has clearly become cheaper; even many no-name manufacturers have sw itched over
to it. Two 512 MB modules, for example, can already be had for $250. In addition to that, finally there are
currently motherboards for the Xeon Socket 604, which can operate w ith unbuffered memory - provided they
are based on the E7505 chipset from Intel. Until now , this market segment was dominated by the space-
hogging WTX boards, but now many manufacturers also offer such systems in the usual ATX format, and a
Dual Socket 604 board fits w ithout any problems into a conventional desktop tower. The prices for such
motherboards start at around $260. Due to the price situation, the dual-capable E7505/Placer chipset is an
obvious choice, especially for the Xeon.
Cinema 4D with scene renderings
Even w hen taking HyperThreading processes into consideration, there are big everyday advantages for
certain users w ho have a PC equipped w ith dual processors. As a result, softw are for graphics rendering,
video and audio encoding and simultaneous operation of tw o or more calculation-intensive applications profit
from the impressive increases in performance. In the area of graphics rendering, there is dual-capable
softw are, such as 3D Studio MAX, Cinema 4D and Lightw ave; in video encoding, there is, for example,
MainConcept Encoder, Pinnacle Studio 9 or Flask Mpeg.
In addition to multiprocessor softw are usage, the user's w ork environment is also slowly changing. Because
graphics cards often have tw o slots, and monitors are relatively inexpensive, many users already use tw o
displays. Ambitious home users can tell you a thing or two about that: w hoever wants to encode a video and
start a game at the same time w ill immediately experience the limits of a single processor system. An
intelligently configured dual platform reacts differently.
Here, w e analyze Intel's dual-processor capable E7505/Placer chipset and offer tips for memory usage. In a
subsequent article, using a self-programmed tool, we w ill show that increases in performance can be achieved
w ith certain applications, as long as certain threads are not managed by an operating system but are
manually assigned to a CPU. In connection with that, w e have also completed a comparison test of E7505
motherboards, w hich w ill be posted soon on the website.
W ith 143 mm2, the surface size of the silicon die seems bigger, because the 875 requires only 100 mm2. The
HUB 2.0 interface and the memory controller account for the larger surface area. This also keeps the price low
for the motherboard manufacturers. For the E7505, you have to pay $100 per unit in quantities of 1,000 -
tw ice as much compared to the 875.
The E7505 Northbridge (a.k.a. Memory Controller Hub, abbreviated as MCH) is typically bundled with the ICH4
and P64H2 Southbridge. The ICH4 is connected to the HUB 1.5 interface and clocks a speed of 66 MHz. This
interface can transfer files to Northbridge at a maximum speed of 266 MB per second with an 8 bit bus width.
The ICH4 (82801DB) Southbridge, based on a 250-nm process, offers connectivity for six USB 2.0 ports, four
ATA100 drives, a 100 MBit LAN chip, an AC97 sound decoder and support for a maximum of six PCI master
devices, each w ith 133 MB per second bandwidth.
Intel's P64H2 Southbridge
Things w ork differently with the P64H2 (82870P2) Bridge. It w as designed for the fast PCI 64 and PCI X
interfaces. The PCI 64 interface corresponds to Version 2.3. Both operate in 64 bit mode. All motherboards
w ith an E7505 chipset in the WTX format have connection possibilities for a maximum of three PCI 64 and one
PCI X cards. PCI 64 operates either with 33 MHz or 66 MHz, resulting in transfer rates of betw een 266 MB/sec
and 533 MB/sec (maximum). In comparison, the PCI X operates w ith 66 MHz, 100 MHz and 133 MHz. Data
transfer rates of betw een 533 MB/sec and 1066 MB/sec are reached.
Block diagram of the E7505 chipset with P64H2 Southbridge
Standard cards do not exhaust data transfer rates of 1,066 MB per second. Only high-performance products,
such as SCSI320 cards (320 MB/s) or 10 GB LAN chips (max. 1250 MB per second), w ould be sensible
candidates.
Many PCI cards are capable of performing their services not only with conventional PCI 2.3 slots, but also with
a PCI 64 slot. Examples of these are network cards, RAID controllers and even 56K modems. In order to avoid
incorrect configurations, they have an additional notch on the connection contacts.
The 56K modem operates here w ith conventional 33 MHz in 32 bit mode.
Chipset Price
Like the 875 chipset, the E7505 manages 8 rows (also called pages). Reminder : 1 memory module has either
one row (single page) or two rows (double page). The follow ing table provides a sample calculation for the
respective maximum memory upgrade of the platforms (w ithout ECC) :
Number of possible chips without ECC Number of possible chips w ith ECC
8 9
16 18
Registered and ECC memory from Legacy Electronics w ith CL 2.5 timings
DDR333 Registered and ECC memory from Infineon w ith CL 2.5 timings
To give you a worst case example : Modules w ith 16 GB ECC system memory can consist of 144 chips - an
enormous burden for the Memory Controller Hub ! However, only 128 of these chips are used for actual
memory functions, w hile the rest is used for administrative tasks.
Classical memory is alw ays available in unbuffered versions. W hat’s new is registered memory (previously
referred to as buffered memory). The more chips a memory controller has to manage, the less clear the data
signals w ill be.
And now the trick : If you put a small manager in front of the nose of individual memory chips, every row /page
w ill trick the memory controller into believing that only one chip is available. And this improves the signal
quality and data security. But this comes at the cost of speed because the small register chip causes a short
time delay in the electrical signals.
As a rule, every Socket 604 Xeon CPU is suitable for HyperThreading technology. The E7505 is capable of
simultaneously operating w ith tw o processors, as well as with HyperThreaded applications. As a result, four
processors (tw o physical and tw o virtual) are available for the operating system. Nevertheless, the chipset
has only one CPU interface, w hich means that both processors have to share one bus. At a speed of 133 MHz
(533 MHz QDR), a bandwidth of 4.2 GB per second results. In a worst-case scenario, each virtual CPU w ill
receive only one data flow at only 1 GB per second. However, this could have negative effects only with some
OpenGL applications.
On the left, the Xeon and on the right, the P4 Northwood from Intel
The Intel Xeon (code name "Prestonia") is based on the same core as the Pentium 4 "Northwood". The latter
operates with an FSB of 200 MHz (800 MHz QDR), and compiles at 6.4 GB per second. In order to balance out
the up to 34% low er bandw idth w ith the Xeon, Intel also offers models w ith 1 or 2 MB L3 cache, beginning
w ith the 2.4 GHz versions.
On the left, the big WTX format and on the right, the ATX format
Compared to standard ATX boards, Xeon w orkstation boards have considerably more units, including, for
example, PCI64/X interfaces, tw o Southbridges, LAN chips, voltage regulators, CPU socket or an additional
SCSI controller. In order to accommodate the higher number of components, larger boards in WTX standard
are required. These have a 32.94% larger surface area, measuring 33 x 33.5 cm compared to the ATX boards
(30.5 x 24.5 cm). Boards w ith a WTX form factor do not fit in a conventional home PC case. The manufacturers
MSI and Tyan also offer motherboards w ithout the additional components, such as P64H2 Bridge and LAN in
an ATX format. At any rate, installing them in a conventional tow er would not be a problem.
Because w e are talking here about a dual CPU platform, the processing unit's power loss is also doubled. The
fastest Xeon models w ith a Prestonia 2-M core and 3.2 GHz speed have, as a pair, a maximum pow er loss of
184 watts. Added to that are board components (an average of 50 w atts), a high-performance graphics card
w ith 70 w atts, and a large memory upgrade - all together, it quickly uses up 350 watts.
This overloads the pow er supply to the motherboard. As a result, the boards in WTX format have another
power adapter standard, w hich goes by the name of EPS12V. They have connections w ith more pow er and
mass cores, as w ell as w ider plugs in order to distribute the load better. As with the ATX form factor, the
power pins are also made of gold in order to attain a low er resistance and to therefore improve the quality of
the signals.
On the left, a 24-pin WTX plug and on the right, a 20-pin ATX plug
On the left an 8-pin WTX plug and on the right, a 4-pin PWR plug
The "20/24P" marking on the large voltage connection indicates that it can operate w ith the 24-pin W TX as
w ell as w ith the 20-pin ATX memory. The same applies as well to the "12V-8/4P" marking on the small AUX
connection - it supports the 8-pin as w ell as the 4-pin connections. Each of the four missing leads is a
redundant voltage pin for load sharing.
For the pow er adapter with the EPS12V standard, additional +12V, +3.3V, +5 V and mass leads are connected
to the board.
The E7505 Northbridge offers support for AGP graphics cards, w hile most motherboards have a "Pro" slot.
W ith the Pro versions, the card is supplied w ith additional voltage pins.
Signaling Level
Data Rate AGP 3.0 1.5 V3.3 V
PCI-66 Yes Yes No
1 x AGP No Yes No
2 x AGP No Yes No
3 x AGP Yes Yes No
4 x AGP Yes No No
Support for the 3.0 standard is also offered, and all graphics cards available on the market can be used
w ithout any problem.
OpenGL
DirectX 9a
13. Video
14. Video, Continued
Audio
15. Applications
16. Applications, Continued
Synthetic
Applications already optimized for HyperThreading see performance gains from the use of two physical CPUs.
In view of system costs, it is therefore worthw hile for users to go with a Dual Xeon as their next system if
most of their time is spent rendering or encoding.
In the subsequent articles, w e w ill show how the various E7505 motherboards measure up in a head-to-head
comparison. We w ill also soon publish an article on how to increase performance by using a self-programmed
tool, w hich can assign tasks to certain CPUs. This tool takes away automatic task assignments from the
operating system and forces an application to run on a manually-specified CPU.