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Asus P4T533

The P4T533, Asus’ new flagship i850E motherboard poised to raise the performance bar for enthusiasts alike. But does it deliver? Read on for what will most assuredly be some surprising results.

Introduction

Asus is a name synonymous with stability, quality and performance, which many computer enthusiasts have discovered with recent motherboards. Asus is also an innovator, and they are here once again to push that bar upwards. Today we are going to show you the newest motherboard from Asus designed for the absolute best performance using a new form of RDRam.

First lets take a little history lesson with Asus and their Intel i850 chipset-based Socket 478 motherboards. Their first entry into the Pentium 4 i850 socket 478 market was with the Asus P4T-E. This original board only supported up to the 400MHz (Quad Pumped) speeds of the Pentium 4 Northwood A CPUs. The memory used standard 16bit RIMM sockets allowing up to 2GB of PC800 RDRAM at 3.2GB/sec. Included with this motherboard were dipswitches, which you could use to overclock with as well as a fully jumperless option where the settings could be changed in the BIOS. Their next leap up was the Asus P4T533-C i850E based motherboard. This board features the new i850E chipset allowing up to 533Mhz FSB Northwood B Pentium 4 CPUs. This motherboard also brought support for 2GB of 1066Mhz RDRAM, allowing up to 4.2GB/sec of bandwidth. This motherboard has been hailed for its great performance and stability with P4 CPUs. But one feature it lacks is 1Mhz FSB increments up to 200Mhz, it is limited by the overclocking options available. Welcome in Asus’s third installment of a RAMBUS motherboard based on the i850E chipset, the P4T533. So what else could they put on the table to make it that much more enticing you ask? How about 32bit RAMBUS?

It seems that with each new P4 i850 motherboard from ASUS they have raised the memory support as much as they could. Starting with PC600 and PC800 16bit RAMBUS for 3.2GB/sec in the P4T-E and then upgrading to support PC1066Mhz 16bit RAMBUS for 4.2GB/sec in the P4T533-C despite the i850E actually officially supporting that speed. The new P4T533 supports PC800 32bit RDRAM (RIMM 3200) and PC1066 32bit RDRAM (RIMM 4200) for 4.2GB/sec of bandwidth. But wait a minute, 1066Mhz 16bit RAMBUS also has 4.2GB/sec bandwidth, so what’s the advantage? Let’s take a quick look at what we know about RAMBUS.

First some quick definitions, Rambus Inc. is the company that developed the RDRam technology that is built onto the DRAM chips and the logic devices that control it. The module itself that these RDRAM chips are integrated onto is called a RIMM. The three most common RIMMs that are used today are PC600, PC800 and PC1066 16bit modules. The PC rating indicates the speed the RDRAM runs at in Megahertz. To figure out the bandwidth you have with RAMBUS you multiply the speed of the RDRAM times the width of the bus. Let’s take the PC800 module for example. We would say 800Mhz x 2 = 1600. Breaking it down it looks like this: 800Mhz speed of the RDRAM Multiply it by 2 (16bits = 2 bytes) and get a result of 1600 or 1.6GB/sec. So for one single RIMM operating at 800Mhz we have 1.6GB/sec of bandwidth. Now, when the P4 rolled out with a 400Mhz data bus, Intel wanted to find RAM that would match the bandwidth of the P4 bus. The solution was Dual Channel RAMBUS which used two RIMMs to double the bandwidth to 3.2GB/sec which matched the P4’s FSB. With Dual Channel RAMBUS there are two channels on the motherboard, channel A and channel B. There are 2 RIMM slots per channel. However, in order for dual channel to work you have to have at least one RIMM in each channel; therefore it has to be installed in pairs. Those RIMM slots not occupied by a RIMM need to have a CRIMM installed. A CRIMM is basically a pass through module that is needed so that the signal can pass through all the RIMM slots from the beginning of channel A (and B) to the end of channel A (and B) with the terminators being on the motherboard itself.

With the introduction of the i850E the Pentium 4 FSB was raised to 533Mhz which consequently raised the bandwidth. At this speed Dual Channel PC800 was not enough. Intel missed getting the official PC1066 spec put into the i850E chipset. So it was up to motherboard manufacturers to take up the slack, and they did. Most i850E motherboards support the PC1066 memory speeds in their BIOS. Dual Channel PC1066 gives us 4.2GB/sec of bandwidth satisfying the Pentium 4’s bus.

So what exactly is a RIMM 4200 then? To put it in simple terms a RIMM 4200 is Dual Channel PC1066 memory squeezed onto only one RIMM. Gone are the days of installing RAMBUS in pairs, now only one RIMM is required. Instead of having channel A and B separated on the motherboard it is now all built into ONE RIMM with the terminators on the RIMM itself. This means you only have to install one RIMM on your motherboard and you will still enjoy the benefits of dual channel RAMBUS. You still need a CT-CRIMM on the slots not occupied as it acts as a terminator for the series. What they have done is moved the terminators off the motherboard and onto the RIMMs themselves packing the whole dual channel scheme onto one RIMM. This is able to happen because of the 32bit bus. You basically have half the RIMM being channel A (16bit) and the other half being channel B (16bit) to equal one RIMM operating in full dual channel mode. The benefit here is obviously not for speed, but rather to cut costs. By placing the terminator resistors on the RIMMs they no longer have to design them into the motherboard, saving PCB space. You will find two versions of 32bit RAMBUS, RIMM 3200 and RIMM 4200. RIMM 3200 runs at 800Mhz for 3.2GB/sec of bandwidth while RIMM 4200 runs at 1066Mhz for 4.2GB/sec of bandwidth. The advantage boils down to the fact you do not have to install in pairs, and it cuts cost for motherboard manufacturers and OEM’s.

In the first picture you will see our Samsung 512MB 32bit RIMM 4200 used in this review. If you take a close-up look at them you will see the notches are different from 16bit RIMM. The slot is therefore different as well. 32bit RIMM has 232 pins while 16bit RIMMs are 184 pins. The CRIMM for 32bit RIMMs has the terminators on it.

For comparison here is a Samsung 16bit RIMM and RIMM slots.

One thing you must be cautious of with 32bit RAMBUS is not to call it PC4200. It does not run at 4200Mhz, it runs at 1066Mhz. The naming scheme is RIMM 3200 and RIMM 4200 indicating 32bit RAMBUS at 800Mhz and 1066Mhz respectively. If you work out the math the bandwidth matches that of the naming scheme also.

Now that we understand that lets take a look our P4T533.