Choosing the Components
This started out as a comparison between different current memory technologies, but it just can’t be done in that context. In order to do a fair comparison of different memory types you would need to have one chipset that supported all of the different types being tested, and there just isn’t a chipset that will do that. On top of that, you would need to have at least two, if not three, chipsets in order to confirm your results are valid (i.e., that the chipset used performs equally with all types of memory). So given that we can’t perform a direct memory comparison we will have to settle for a comparison of both the chipset and memory – a packaged comparison. There is also the concern that each mainboard and chipset used will be fully optimized and will give us a valid comparison, and from my experience I would say for the most part that will be true for the results given. Gee, I think I just wrote a disclaimer…
For this series of tests I wanted to be able to compare all the current mainstream memory on the market. That means I had to find chipsets and mainboards that supported PC133 SDRAM, VCM SDRAM, DDR SDRAM and RDRAM. There is currently only one CPU platform that supports all those memory types: The Intel Pentium III. Since the i820 is the only PIII chipset supporting RDRAM, I was limited and used a Soyo 6ICA sent to me for evaluation a long time ago. It never made it past the pilot stage, but from what I’ve seen it is typical in performance. VIA makes one of the few chipsets that supports both VCM and SDRAM, so I used the Soyo 7VMA, which is based on the PM133 chipset (same as a 694X but also has integrated video that wasn’t used). For the DDR SDRAM I used the VIA Apollo Pro 266 based Soyo 7VDA. Just to make sure all the results were in line I also tested SDRAM on the Intel 815EP based Soyo 7IS2.
I chose the Slot 1 / Socket 370 platform and an Intel Pentium III CPU for this series of tests for one reason, so I could include RDRAM. RDRAM is not available for Socket A (the others are), and only RDRAM is currently supported for the Pentium 4. The PIII 800EB was used because its performance is in the upper middle of the speed range of available CPUs, and should give a good indication of what users can expect. In future tests I’ll take a look at Socket A using SDRAM, VCM SDRAM and DDR SDRAM, and when available (should be about August or so) I’ll take a look at Pentium 4 systems using RDRAM, SDRAM and DDR SDRAM. The P4 comparison should be interesting.
RDRAM still hasn’t made the impact on the market that Intel (and Rambus) expected it would. With a PIII CPU the bandwidth is limited by its maximum FSB speed of 133MHz. That may be a different story with the P4, but I’ll reserve judgment until I see some comparison testing. DDR SDRAM performance is also somewhat limited by the bandwidth of the PIII, but it does seem to have an edge over SDRAM with a Socket A CPU and its 266MHz FSB. It will be interesting to also see how it fares with the P4 when VIA releases its P4 DDR SDRAM chipset. I guess what I’m saying is that the PIII is the only CPU that allows me to test all four types of memory, and while it may not be the best choice to judge DDR SDRAM and RDRAM with, it is all we have, currently.
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