Motherboards in 2000 Preview - Part 1: Chipsetsby Anand Lal Shimpi on December 6, 1999 12:44 AM EST
- Posted in
The i820 is a reality, in spite of its promotion of the very expensive Rambus platform. We will find Intel's 820 chipset being used more on motherboards as we move into the New Year. Intel has faced quite a few problems with the 820 chipset, the first being the chipset's untimely delay, announced just before the release of the chipset's CPU counterpart, the Pentium III E.
The show stopping bug that forced Intel to pull the plug (unintentional rhyme) on the chipset was officially a "layout issue" involving motherboards built with 3 - RIMM slots. Intel insists that the problem was not related to the chipset nor the Rambus memory technology and thus made it very clear that motherboard manufacturers implementing the i820 chipset into their designs should opt for a 2 - RIMM memory configuration. Because this dramatic change was issued in a very impromptu fashion, many motherboard manufacturers at Comdex were displaying their i820 samples with 3 - RIMM slots while the actual shipping boards will feature 2.
The second problem with the i820 chipset turned out to be the utterly incredible cost of RDRAM. While we all expected RDRAM to be noticeably more expensive than PC100/133 SDRAM, we did not expect it to be retailing for over 5 times the price of PC133 SDRAM. With a 128MB RDRAM module going for around $1000, it is highly unlikely that a user would be able to fill more than two RIMM slots in the first place without resorting to auctioning off their car. The RDRAM approach is obviously very impractical for most users, which left motherboard manufacturers between a rock and a hard place, the latter being Intel's pressure to push forth the i820 platform.
The collective solution seemed to be to go for what is known as the "2 + 2" memory configuration on i820 boards. By making use of a fourth chip on an i820 based motherboard (the first three being the I/O Controller Hub, Memory Controller Hub and FirmWare Hub), the Memory Translator Hub enables the support for SDRAM on an i820 based motherboard. The "2 + 2" comes in to play when you look at the layout of memory slots on the board: 2 RIMMs + 2 DIMMs. A single MTH supports up to two DIMM slots, so in order to support 4 DIMM slots (which some motherboard manufacturers have decided to do) you must have two MTH chips. Keep in mind that these MTH chips do help to increase the cost of the board.
Obviously, Intel doesn't favor this approach because they are trying very hard to push the i820/Rambus platform into the hands of consumers. Realistically speaking, the inclusion of the MTH is about the only way to guarantee somewhat positive sales for the i820 due to the incredible price of Rambus. While there will be some that opt for the i820 + Rambus setup, the resulting price tag is entirely too high for a simple desktop workstation.
The inclusion of the MTH naturally degrades the level of performance of the setup simply because it is translating memory requests after they already reach the i820's Memory Controller Hub. The reason the requests are not intercepted directly is because the i820 does not natively support SDRAM. The performance of the i820 + MTH + SDRAM is noticeably slower than the simple BX + SDRAM solution we've been using since April 1998, and it costs more.
This whole situation would be much better if the i820 did have native SDRAM support, but that wasn't about to become a reality with Intel intent on making Rambus the next memory standard. In the future, the price of RDRAM will have to decrease in order for it to become an affordable option, and for Intel's sake, that better happen soon if the i820 is to become an accepted standard.
The question of whether or not the i820 would be featured on dual processor motherboards was answered when we saw quite a few dual i820 boards. We even saw some dual 820 boards with dual MTHs and 4 DIMM slots. In our minds this was a very disgusting picture, from a performance perspective that is, since anyone that would go after a dual CPU setup would definitely not want their memory performance hindered by an MTH.
On the Comdex show floor, the i820 had a huge presence among the motherboard manufacturers that we visited, outweighing all of the BX, Apollo Pro 133A and AMD 750 solutions combined. Unfortunately, this wasn't an indication of great demand for i820 products, rather a push from the guys upstairs to show off the i820 platform.
The first i820 boards will be falling into the $150 - $179 price range. This will put them at around the same level as the current crop of Athlon motherboards on the market. Adding on a single or dual MTHs onto the board helps drive that price up even further. Tack on the cost of RDRAM or subtract the performance penalty provided by the SDRAM + MTH combination, and all of the sudden those "expensive" Athlon motherboards become much more appetizing. Even more appetizing is your current BX setup that you were so eager to get rid of.
Going into the New Year expect to see a number of i820 based motherboards, and expect to be buying very few of them.