Expansion Slots

Always a consideration, the expansion potential of your next motherboard should be sufficient to tend to your needs for at least the next year. Since your motherboard should be rarely upgraded when speaking in terms of individual upgrades to your system (usually a motherboard upgrade goes hand in hand with a CPU upgrade), you’ll want to make sure that your next motherboard is capable of supporting more than enough devices than you have installed. Although you may have a need for only 3 PCI slots now, a couple months down the road a new peripheral may be on your wish list, and you definitely don’t want to have to upgrade your motherboard just so you can take advantage of the latest TV tuner.

There are two major expansion slot configurations motherboard manufacturers have chosen to unofficially standardize known to AnandTech readers as the 5/2/1 and 4/3/1 expansion slot configurations. The configuration notation used by AnandTech represents the number of PCI/ISA/AGP slots on the motherboard. That notation will soon change in 1999, the why behind that change will be discussed a little later.

Another consideration when looking at expansion slots is whether or not the expansion slots are capable of accepting full-length cards. Older devices such as many 16-bit ISA sound cards happened to be unusually longer than most other cards, and thus required a larger clearance on a motherboard to be installed properly. While most PCI cards do not suffer from this same handicap, owners of 3dfx Voodoo2 cards (with the exception of the Canopus Pure3D-2, which is a full 1" shorter than other V2 cards) will also share the need for full length PCI slots.

The idea of having the full-length AGP slot emerged in 1998, however most full-length AGP cards are reserved for high-end workstations and are rarely seen in the desktop market. Needless to say, motherboard manufacturers have taken this suggestion into account, and many newer BX boards now accept full-length AGP cards.

Memory & Cacheable Area

In spite of the chipset's support for EDO DRAM, no BX boards have been made commercially available with SIMM slots, DIMMs are the current fad and expect them to stay that way until Intel’s next chipset, the i820 (codename Camino) catches on. You'll find boards with either 3 or 4 DIMM slots on them, and unless you plan on using more than 3 DIMMs there is no real advantage to going with a board that has 4 DIMM slots versus one that has 3 slots. There is no performance increase or decrease related to using many smaller DIMMs in comparison to one larger DIMM (i.e. 2 - 32MB vs 1 - 64MB). It is best to purchase one larger DIMM so you don't have to worry about running out of space for memory expansion just in case you feel the need to purchase more memory when the price drops. This suggestion is somewhat overly simplified due to the fact that in 1999, there are some new factors that one must take into account when purchasing DIMMs of larger sizes, a topic that will be discussed later on in this comparison.

Unlike the older Socket-7 motherboards you may be familiar with, Slot-1 Pentium II boards don't have a Cacheable Memory Limit set directly as a function of the motherboard. Instead, it is the processor's duty (courtesy of the on-card L2 cache of the Pentium II) to cache all DRAM. Older Pentium II's with 512KB of L2 cache can cache up to 512MB of RAM, while the newer Pentium II chips (350/400) can cache up to 4GB of system memory...try maxing that limit out with 4 DIMM slots.

The cacheable memory area on the original Celeron processors is, naturally, 0MB. Yes, you read right, that is zero megabytes, this is because the original Celeron's don't have any L2 cache, and if you don't have any L2 cache it is impossible to use the L2 cache to cache a certain range of system memory to speed up access to it. The newer Celeron processors, with 128KB of integrated L2 cache, allow for a cacheable memory area of 4GB of system memory like the newer Pentium II processors, so once again, you won't experience any problems caching the RAM you decide to stick into your new BX motherboard.

Index What to look for in 1999

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