by Ilya Gavrichenkov
03/10/2003 | 02:45 PM
Even though dual-channel chipsets for Pentium 4 processors have already started their expansion into the market (see our Intel E7205 and SiS655 reviews), the dual-channel DDR SDRAM will reach its peak popularity in April-May timeframe. At that time Intel will introduce new processors with 800MHz bus and will start shipping new dual-channel chipsets targeted at the High-End and Mainstream market. To be more exact we should point out a few key dates to you. The first Pentium 4 processor with 800MHz Quad Pumped Bus supporting Hyper-Threading technology will be released in the second half of April. This newcomer will be Pentium 4 3.0GHz. It will be announced together with the i875P chipset (also known as Canterwood), which will support the new fast bus. Intel planned that i875P will not become a mass product, it will be used only in high-performance workstations. In fact, i875P is positioned as a replacement for i850E. The new Pentium 4 processors with 800MHz bus will become mass products in the middle of May. At that particular time Intel is going to enlarge the new Pentium 4 family by introducing three new CPU models: 2.40C, 2.60C and 2.80C GHz supporting the same bus and Hyper-Threading technology. Together with the CPUs supporting the new faster Quad Pumped Bus, Intel will launch a number of mass core logic sets also supporting this bus. They will be: i865G, i865P and i865PE (also know as Springdale family). These chipsets will be the ones to replace i845 family and to bring the dual-channel DDR SDRAM support into the mass market.
<%BANNER[article]%>As a result, Intel’s plans concerning the changes in the chipset market look as follows:
As we see, Performance and Mainstream market segments will be occupied by the chipsets supporting dual-channel DDR SDRAM. This is not at all surprising. The bandwidth of Quad Pumped Bus used by Pentium 4 processors is higher than the bandwidth of the regular 64bit DDR SDRAM. Therefore, if the chipset makers want to get the fastest platforms possible, that is the platforms with the corresponding memory bandwidth, they have to built two simultaneously working DDR SDRAM controllers into their products. In this case they can easily achieve well-balanced functioning of the FSB and the memory bus. To prove the above made statement, we would like to offer you a table with the bandwidth values of different Quad Pumped Buses and major memory types used in modern systems:
| Bus | Bandwidth, GB/sec |
| 400MHz Quad Pumped Bus | 3.2 |
| 533MHz Quad Pumped Bus | 4.2 |
| 800MHz Quad Pumped Bus | 6.4 |
| Memory type | Bandwidth, GB/sec |
| Single-channel DDR266 SDRAM | 2.1 |
| Single-channel DDR333 SDRAM | 2.7 |
| Single-channel DDR400 SDRAM | 3.2 |
| Dual-channel DDR266 SDRAM | 4.2 |
| Dual-channel DDR333 SDRAM | 5.4 |
| Dual-channel DDR400 SDRAM | 6.4 |
| Dual-channel PC800 RDRAM | 3.2 |
| Dual-channel PC1066 RDRAM | 4.2 |
This way only dual-channel DDR333/DDR400 SDRAM or PC1066 RDRAM will suit for building well-balanced systems based on Pentium 4 processors with 533MHz bus. Moreover, the transition to faster 800MHz bus will require only dual-channel DDR400 SDRAM. So, we have every right to state that the transition to dual-channel DDR400 SDRAM is hundred percent justified.
There is still quite a bit of time left before the new processors and chipsets come to the market. However, you should get ready for the sharp increase in the bus speed between the CPU and system memory well in advance. Luckily, our site appeared one of the first in the world to get the opportunity to take a closer look at the new systems working with 800MHz bus before their official announcement. So, we are going to devote this entire article to the features and peculiarities of the upcoming i865 and i875 chipsets and will try to evaluate the performance growth provided by the use of faster 800MHz Quad Pumped Bus with dual-channel DDR memory.
First of all I would like to point out that the new chipsets aimed at 800MHz bus support, namely i865 and i875, do not differ too much from one another. I suggest discussing the differences between them a bit later in this review. And now let’s have a look at the major features of the new i865 solution, as this is exactly the chipset, which should be regarded as a basic platform for the future Pentium 4 systems.
So, the new chipsets from i865 family will bring into the world a few brand new ideas. In terms of the number of innovations, these solutions are far ahead of the entire i845 family. i865 core logic will receive the support of 800MHz system bus, dual-channel DDR400/DDR333/DDR266 SDRAM, AGP 8x and the so-called Communications Streaming Architecture for Gigabit Ethernet implementation. Besides, the solutions from i865 family will use the new ICH5 South Bridge with SerialATA and RAID support. To back up my story by some clear evidence let me offer you a flow-chart for i865PE, which is the most advanced solution in the entire Springdale dynasty:
So, in general, the chipset is based on a pretty common architecture and includes two bridges connected with the same Hub Link 1.5 bus. However, the bandwidth of the major buses has become significantly higher now. Thus, the processors bus bandwidth can now reach 6.4GB/sec with 800MHz system bus. The higher upper limit for the FSB frequency as well as Hyper-Threading support built into the chipset will make i865 chipsets very up-to-date throughout the whole year 2003. Mainboards based on i865 will be able to work with all Pentium 4 (Northwood) processors as well as with the first Pentium 4 (Prescott) processors manufactured with 90nm production technology.
However, in 2004 already Intel is going to replace these chipsets again. Moreover, by then the company will also change the processor socket form-factor. New Prescott based CPUs released at that time as well as their Tejas based successors will use the new LGA775 socket and will work with new Grantsdale based chipsets. Grantsdale chipset family is expected to be using dual-channel DDR-II memory and will be provided with ICH6 South Bridge. Although this is still a too far-away prospect.
Despite the fact that the number of MCH contacts by i865 has been increased up to 932, the chipset remained of the same size as i845G
Since DDR-II memory hasn’t yet got widely spread in the market, i865 chipsets use the regular DDR SDRAM. The memory frequency can be set to different rates depending on the system bus frequency. This way, if the FSB frequency is 400MHz, i865 will be able to work with DDR266 SDRAM, in case of 533MHz FSB – with DDR266 or DDR333, for 800MHz FSB – with DDR266, DDR333 (to be more exact, with DDR320) and DDR400 SDRAM. The dual-channel memory access is implemented in i865 via the two built-in memory controllers. Therefore, i865 can work in dual-channel mode (in this case you will have to use identical memory modules pairs) as well as in single-channel mode. The maximum performance can be achieved when you use memory modules in pairs and take advantage of the fully-fledged dual-channel access. Moreover, if all the memory modules used in the system are of the same type, the chipset can activate the so-called Dynamic Mode, which will improve the performance a little bit more.
Speaking about the features of the upcoming chipsets, which are to come out very soon now, we should definitely point out that all of them will support AGP 8x interface. In other words, Intel has finally made up its mind to implement in all its new chipsets the support of this protocol, which allows transferring the data to and from the graphics subsystem at 2.1GB/sec.
Well, this could have been the end of the story about the new features introduced in the North Bridge (Memory Controller Hub) of i865, but... The chipset North Bridge features one more bus with 266MB/sec bandwidth, which is intended for CSA (Communications Streaming Architecture) implementation. The major idea of this bus is to offer the possibility to create high-speed gigabit network connections. Due to the fact that there is a special bus for network needs, the network requests get processed much faster, and the CPU workload drops down significantly. Moreover, due to CSA, all network controllers connected to this bus can work with the memory directly. Intel suggests using Intel PRO/1000 CT chip as a network controller for the CSA.
Intel will be offering three versions of its i865 chipset:
It is also very important that the reference design of any i865 based mainboard implies a 4-layer PCB. This allows us to expect the new Springdale based solutions to be not very expensive and the mainboard prices to drop down to the current level of i845PE and i845GE based boards.
Also we should pay due attention to the new ICH5 South Bridge, which will be used in i865 based mainboards. The completely new feature implemented in this South Bridge is the support of two SerialATA ports. However, there are a few smaller innovations, which we would also like to mention here.
First of all, I would like to draw your attention to the fact that the new ICH5 South Bridge supports up to 8 USB 2.0 ports. It still supports 6-channel AC’97 sound (now three separate codecs can be used) and two ATA/100 channels. Intel is still principally against ATA/133 support, trying to push the industry directly towards the new SerialATA standard.
As for SerialATA, ICH5 supports two SertialATA-150 channels. In other words, ICH5 allows connecting up to 6 ATA devices. It is also important that the SerialATA controller integrated into the new South Bridge doesn’t require any specific drivers.
But the most interesting thing about the new ICH5 is different from what we have just mentioned. The matter is that ICH5 will become the world’s first chipset South Bridge ever supporting the RAID function! A special version of the ICH5 aka ICH5R (Intel 82801 ER chip) will support RAID 0 (striping) and will cost only $3 more than the regular ICH5. Although you will be able to build a RAID array only of SerialATA drives, it will be a very easy thing to do: any time the second HDD is connected you can create an array without any reinstallation of the operation system and the like.
In the future, Intel promises to improve the function of the built-in RAID. They tend to introduce support of RAID 1 arrays (mirroring) and Windows 2000. In the meanwhile, Intel’s RAID function will work only in Windows XP.
Speaking about i865, we can’t help mentioning its elder brother, Intel 875 chipset. On the one hand, it has practically the same features set, but on the other hand, it boasts some peculiarities, which allow regarding it as a solution for high-performance workstations. So, all in all, there are two major differences between i865PE and i875. Firstly, i875 supports ECC, which is a must for chipsets used in reliable high-performance systems. And secondly, this solution supports the so-called Intel Performance Acceleration Technology or simply Turbo Mode.
According to Intel, the use of special Turbo Mode can increase the system performance in case 800MHz bus and dual-channel DDR400 SDRAM are used. By involving internal reserves, the latency between the FSB and the main memory is lowered in Turbo Mode. However, to activate this mode you don’t need any specific memory for your system: the entire optimization is implemented in the chipset architecture and mainboard BIOS. Turbo Mode is expected to speed up i875 by 3-5% compared to i865 family.
The support of ECC and Turbo Mode are the only two major differences between the i865 and i875 chipset families. There are no other differences between them, that is why I assume it is high time we summed things up.
| Intel 875 | Intel 865G | Intel 865PE | Intel 865P | |
| Market segment | Performance | Performance/ Mainstream | Performance/ Mainstream | Mainstream |
| Supported processors | Pentium 4/ Prescott | Pentium 4/ Prescott/ Celeron | Pentium 4/ Prescott/ Celeron | Pentium 4/ Celeron |
| FSB frequency | 800/533MHz | 800/533/400MHz | 800/533/400MHz | 533/400MHz |
| Hyper-Threading technology | + | + | + | + |
| Intel Performance Acceleration Technology | + | - | - | - |
| DIMMs per channel/ Max. memory size | 2 DIMMs per channel / max. 4GB | 2 DIMMs per channel / max. 4GB | 2 DIMMs per channel / max. 4GB | 2 DIMMs per channel / max. 4GB |
| Supported memory types | DDR333/ DDR400 | DDR266/ DDR333/ DDR400 | DDR266/ DDR333/ DDR400 | DDR266/ DDR333 |
| Supported system bus/memory frequencies | 800/DDR400 800/DDR320 - 533/DDR333 - - | 800/DDR400 800/DDR320 800/DDR266 533/DDR333 533/DDR266 400/DDR266 | 800/DDR400 800/DDR320 800/DDR266 533/DDR333 533/DDR266 400/DDR266 | - - - 533/DDR333 533/DDR266 400/DDR266 |
| ECC support | + | - | - | - |
| Graphics slot | AGP 4x-8x (1.5V/0.8V) | AGP 4x-8x (1.5V/0.8V) | AGP 4x-8x (1.5V/0.8V) | AGP 4x-8x (1.5V/0.8V) |
| Integrated graphics | - | Enhanced Intel Extreme Graphics | - | - |
| CSA port for Gigabit Ethernet | + | + | + | + |
| Number of PCI Masters | 6 | 6 | 6 | 6 |
| IDE | UDMA66/100 | UDMA66/100 | UDMA66/100 | UDMA66/100 |
| Serial ATA ports | 2 SATA150 ports* | 2 SATA150 ports* | 2 SATA150 ports* | 2 SATA150 ports* |
| USB ports | 8 USB 2.0 ports | 8 USB 2.0 ports | 8 USB 2.0 ports | 8 USB 2.0 ports |
| Power Management | ACPI | ACPI | ACPI | ACPI |
| LAN MAC/PNA | + | + | + | + |
| AC’97 | + | + | + | + |
| Hub Interface | Hub Link 1.5 | Hub Link 1.5 | Hub Link 1.5 | Hub Link 1.5 |
| (G)MCH packaging | 1005 FCBGA | 932 FCBGA | 932 FCBGA | 932 FCBGA |
| ICH packaging | 460 MBGA | 460 MBGA | 460 MBGA | 460 MBGA |
| (G)MCH marking | 875P | 865G | 865PE | 865P |
| ICH marking | 82801EB | 82801EB | 82801EB | 82801EB |
We were very lucky to get hold of a pre-production sample of i865G based mainboard. Even though the chipset launch is expected to take place about two months later Intel already offers the mainboard guys the first chipset revisions. As you understand, the chipset is still quite raw and is not free from some problems, however, it works well enough for us to be able to get some preliminary benchmarks results, which could allow us to evaluate its efficiency and potential. We couldn’t miss this exciting opportunity and are happy to offer you the first benchmarks results for a system built on i865G Revision A1 chipset. We tested the mainboard we had at our disposal in three work modes: with 800MHz FSB and dual-channel DDR400 SDRAM; with 533MHz FSB and DDR266/DDR333 SDRAM. We also used a Pentium 4 2.8GHz processor with the unlocked clock frequency multiplier, which allowed us to run this CPU at 2800MHz set as 21x133MHz and 14x200MHz.
So, in the end we got the following testbed configuration:
We also had the new drivers for Intel chipset at our disposal, which allowed our system to recognize the newest hardware absolutely correctly.
First of all we measured the memory subsystem performance with the help of SiSoft Sandra 2003 benchmark. Here is a screenshot obtained at 800MHz bus and dual-channel DDR400 SDRAM:
As we see, due to extremely high bus frequency and one of the fastest memory types, the bandwidth of the CPU-to-memory bus grew up to very big rates. However, the practical results still do not reach the theoretical 6.4GB/sec making only about 75% of the theoretical value.
Now let’s find out how big will the practical memory bandwidth turn out in case of 533MHz FSB. The next screenshot was taken with DDR333 SDRAM:
And the following screenshot was taken with DDR266 SDRAM:
As we see, the memory bandwidth by Springdale running with 533MHz bus is hardly any different from the memory bandwidth by another dual-channel chipset aka Granite Bay. However, there is nothing to be surprised at: the memory controller of i865 was based on the one borrowed from Intel E7205.
Now let’s check the results of Cachemem tests, which will give us a better idea of the i865 memory controller performance:
| Memory read speed, MB/s | Memory write speed, MB/s | Memory copy speed, MB/s | Latency | |
| FSB 800 MHz, Dual DDR400 | 3150.7 | 1401.6 | 2668.0 | 242 |
| FSB 533 MHz, Dual DDR333 | 2402.5 | 992.2 | 2078.8 | 350 |
| FSB 533 MHz, Dual DDR266 | 2434.9 | 833.3 | 1898.9 | 364 |
The results are again very predictable: the increase in the bus frequency together with the use of faster memory results into bandwidth growth and latency reduction. At the same time, we would like to point out that the use of dual-channel DDR333 SDRAM with 533MHz processor bus doesn’t improve the performance tremendously compared with that in case of dual-channel DDR266. Here the bandwidth is limited by the system bus frequency and not by the memory subsystem performance.
And here are the results obtained in PCMark2002 test:
The advantage of 800MHz bus is evident: we see 23% performance growth.
In conclusion of our mini test session, we would like to try testing the system in some real applications. We thought it would be a good idea to run SYSmark2002 test set, which includes a lot of popular applications:
The advantages of 800MHz bus over 533MHz one can also be seen with a naked eye. As we notice, faster FSB ensures a significant performance growth in real applications too. SYSmark2002 showed that the performance increased by 5-8%. Here we would like to remind you that all the results provided above were obtained with the processor running at 2800MHz. So, you can now see that the increase in system bus frequency of Intel Pentium 4 processors does have a tangible impact on their performance.
The launching of Canterwood, Springdale and Pentium 4 processors with 800MHz bus should become a significant move forward. As we see, speeding up the Pentium 4 bus together with the shift to faster memory improves the performance very noticeably. NetBurst architecture implemented in Pentium 4 turned out perfectly scalable with the FSB frequency growth. Therefore, as soon as Pentium 4 processors with faster 800MHz bus come out, the performance of top Pentium 4 models will get to a totally new level.
Besides that, the new chipset generation intended to support Pentium 4 with 800MHz bus boasts a great lot of new very up-to-date features. Among them we should definitely mention CSA, native SerialATA support and RAID function. As a result, Pentium 4 based systems should become even more attractive this spring.