Asus P4B266-E and P4S333 in the test: Intel 850 versus Intel 845 and SiS 645

Asus P4B266-E and P4S333 in the test: Intel 850 versus Intel 845 and SiS 645


After having dealt with Intel processors several times lately, we would now like to take a closer look at the matching motherboards with the various chipsets currently on the market. With this we are also expanding our mainboard reviews, which so far have only focused on platforms for the AMD Athlon, with a new section.

In our first review we focus primarily on the difference between Rambus and DDR RAM platforms.

In theory, only Rambus should be able to elicit the maximum performance from a Pentium4 and afterwards Intel also officially prescribed DDR RAM support, it wasespecially the competition who spoke of the 'castration of the Pentium4'. We would like to clarify whether this is also true in theory and compare the advantages and disadvantages of the respective storage technology. That's why we let two representatives of the DDR-RAM squad compete against each other and against a Rambus platform.

The ASUS P4B266-E with i845 (D) chipset and were used as DDR RAM platforms the ASUS P4S333 with SiS645 chipset. For the Rambus platform, the Intel D850MD with i850 chipset, known from our processor test, stepped into the breach.

But before we introduce the individual mainboards in more detail and turn to practice, let's consider the different chipsets in theory .

The chipsets

The chipsets in comparison
Features Intel 850 Intel 845D SiS 645 Supported CPU sockets Socket 423/478 Socket 478 Socket 478 Multiprocessor support yes no no Northbridge Intel KC82850 Intel 82845 SiS 645 Southbridge Intel 82801 BA Intel 82801 BA SiS 961 Front-Side-Bus 100/(133) MHz 100/(133) MHz 100/(133) MHz Memory clock 400MHz 100/133MHz 100/133/166MHz Asynchronous memory clock yes yes (3: 4) yes (3: 4/3: 5) FSB overclocking (depending on the clock) up to 133MHz up to 200MHz up to 166MHz m ax.number of dimming slots 4 (Rimm) 3 3 max.Memory 2048 2048 3072 SDRAM support no no yes DDR-SDRAM support no yes yes (dual) RAM bus support yes no no Ultra-DMA/33/66/100/133 yes/yes/yes/no yes/yes/yes/no yes/yes/yes/no AGP 1x/2x/4x yes/yes/yes yes/yes/yes yes/yes/yes max.number of PCI slots 6 6 6 USB ports 4 4 6 USB 2.0 no no no I/O link hubInterface (266MB/s) Hub Interface (266MB/s) MuTIOL (533MB/s)

Everyone should know that Intel initially only relied on Rambus for the Pentium4. This was mainly due to the fact that only Rambus was able to do justice to the high memory throughput of the Pentium4. Because unlike an AMD Athlon, for example, which can already fully utilize its memory throughput with the PC2100, a Pentium4 with 100MHz FSB already brings it to 3.2GB. For optimal performance, the throughput of the memory should always be at least as high as that of the processor. Since Rambus does exactly this and PC2100 does not in normal operation, the step to Rambus from Intel was actually only logical. But the market has largely not accepted the memory, so that Intel is now concentrating more and more on DDR RAM. This is where the i845D comes into play, which is now also officially supported by Intel DDR-RAM. In Intel's documents, the i845D always appears without the descriptive 'D'. It wore this addition in its development phase and it is still often used today to mark the difference to its predecessor, which was designed for SD-RAM.

The i845 (D) also supports DDR-RAM and should thus help the Pentium4 to become more popular. This should also be possible due to the wider spread of DDR RAM and operation that does not require dual-channel technology as with the i850. But at least in theory, you have to accept poorer performance because of the lack of dual-channel support, since the i845D with DDR266 support can only transfer a maximum of 2.1 GB of data. The Pentium4 can deliver up to 3.2 GByte.

This is exactly the distance that SiS has reduced with its SiS645, which, unlike the i845D, already supports DDR333 and thus a maximum of 2.7 GByte data transfer. But there remains a difference of 0.5 GByte that you can useDDR-RAM will probably only be able to close with DDR400 or dual-channel technology.

On paper, the SiS645 is a bit ahead of the i845D. The maximum memory expansion of 3072 MB is a total of 1024 MB higher than that of the i845D and in terms of the maximum number of possible USB ports it is also slightly ahead with 6 to 4. Most customers will probably not need 6 USB ports, so this 'advantage' can be disregarded. Another interesting technology from SiS is the so-called “Multi-Thread I/O Link”, which is supposed to accelerate the data transfer between North and South Bridge. These two components normally communicate via the PCI bus, which can only transfer 133 MB/s. The connection via the multi-thread I/O link from SiS enables 533 MB/s. Intel's 'Hub Interface', which connects the North Bridge with the South Bridge (I/O Controller Hub - ICH), enables 'only' 266 MB/s.

On the next page: The P4B266 -E