Motherboard Selection Criteria (Knowing What to Look For)


Motherboard Selection Criteria (Knowing What to Look For)

I am often asked to make a recommendation for purchases. Without guidance, many individuals don't have any rhyme or reason to their selections and instead base their choices solely on magazine reviews or, even worse , on some personal bias. To help eliminate this haphazard selection process, I have developed a simple checklist that will help you select a system. This list takes into consideration several important system aspects overlooked by most checklists. The goal is to ensure that the selected system truly is compatible and has a long life of service and upgrades ahead.

It helps to think like an engineer when you make your selection. Consider every aspect and detail of the motherboards in question. For instance, you should consider any future uses and upgrades. Technical support at a professional (as opposed to a user ) level is extremely important. What support will be provided? Is there documentation, and does it cover everything else?

In short, a checklist is a good idea. Here is one for you to use in evaluating any PC-compatible system. A system might not have to meet every one of these criteria for you to consider purchasing it, but if it misses more than a few, consider staying away from that system. The items at the top of the list are the most important, and the items at the bottom are perhaps of lesser importance (although I think each item is important). The rest of this chapter discusses in detail the criteria in this checklist:

  • Motherboard chipset. Motherboards should use a high-performance chipset that supports DDR or DDR-2 SDRAM DIMMspreferably one that supports ECC memory as well if you are concerned about catching possible memory errors before they corrupt your data. Also look for PCI-Express x16 video support and Serial ATA or faster hard drive support. The motherboard chipset is the backbone of a system and is perhaps the single most important part you'll consider. I spend the most time deciding on my next chipset because it affects and influences virtually every other component in the system.

  • Processor. A modern system should use a socket-based processor with on-die L2 cache. Evaluate the processor choices you have, and try to get the one with the highest-speed CPU bus (front-side bus). Don't get too hung up on L2 cache size ; a little cache goes a long way. It is more important that the cache run at full core speed (which it will if it is on-die). Current processors such as the Athlon XP, Pentium 4, Pentium D, Celeron 4, Sempron, and Athlon 64 family all meet this criteria. I usually recommend only "boxed" processors as sold by Intel and AMD, which include a high-quality active heatsink as well as installation instructions and a 3-year warranty direct with the manufacturer. If you want to move to 64-bit computing within the next 1218 months, choose the Pentium D, Athlon 64, Athlon 64 FX, Athlon 64 x2, or Pentium Extreme Edition.

  • Processor sockets. For maximum upgradeability and performance, you should stick with a system that uses a socket for the CPU. The main sockets in use today on new systems include Socket A (Socket 462) for the Athlon XP and some Sempron models, Socket 775 for the Pentium 4 and Pentium D, Socket 754 for the Athlon 64 and some Sempron models, or Socket 939 for the Athlon 64FX. As long as your motherboard has one of these sockets, you should be in good shape.

  • Motherboard speed. The motherboard typically offers a choice of speeds, including anywhere from 200MHZ to 400MHz for the Duron/Athlon/Athlon XP-based boards, or from 400MHz to 1066MHz for the Pentium 4based boards . Check to ensure the board you are buying runs at the speeds necessary to support the processors you want to install.

  • Cache memory. All modern systems use processors with integral cache, most of them now having the cache directly on the processor die for maximum speed. As such, there won't be any cache memory on the motherboard in a modern system. The tip is to make sure you are using a processor with full core speed on-die L2 cache because this offers the maximum in performance. All the modern processors now incorporate full-speed on-die L2 cache.

  • SIMM/DIMM/RIMM memory. Current systems use either DDR or DDR2 DIMMs. DDR2 is expected to become the most common memory type for both Intel and AMD systems by late 2006. Older memory types, such as the now-ancient SIMMs and more recent SDRAM DIMM and RIMM memory, are obsolete and should be avoided. What you use depends mainly on your motherboard chipset, so choose the chipset and board that accepts the memory type you want to use. Currently, DDR and DDR-2 SDRAM and RDRAM are the fastest types of memory available, with RDRAM being by far the most costly. SDRAM is now much more expensive than DDR SDRAM because current systems no longer use SDRAM.

    Mission-critical systems should use ECC memory and ensure that the motherboard fully supports ECC operation. Note that many of the low-end chipsets from Intel and others do not support ECC and should not be used for mission-critical applications. This is something you should know before purchasing the system.

    Finally, note that most full-size motherboards support either three or four DIMM sockets, or two or three RIMM sockets. Be sure that you populate them wisely so you don't have to resort to removing memory later to add more, which is not very cost-effective . Many high-performance systems support one or two pairs of dual-channel memory. On these systems, install memory in matched pairs for best performance.

  • Bus type. Current systems offer one to five or more PCI local bus slots and might also offer PCI-Express slots. Be sure the PCI slots conform to the PCI 2.1 or later revision (primarily based on the chipset). Take a look at the layout of the slots to ensure that cards inserted in them will not block access to memory sockets or be blocked by other components in the case. Systems without onboard video should also feature one PCI-Express x16 slot instead of (or sometimes along with) the older AGP 4x/8x slot. A few boards also feature AMR (audio modem riser) or CNR (communications networking riser) slots for special cards that are included with the board to provide sound, modem, or other similar features. If a motherboard has an AMR or a CNR slot but doesn't include the riser card, you should check with the vendor to determine whether riser cards are available with the features you want. If the AMR or CNR riser cards are not available for a particular board, look for boards that don't need to use these slots.

  • BIOS. The motherboard should use an industry-standard BIOS, such as those from AMI, Phoenix, or Award. The BIOS should be of a Flash ROM or EEPROM design for easy updating. Look for a BIOS Recover jumper or mode setting, as well as possibly a Flash ROM write-protect jumper on some systems.

  • Form factor. For maximum flexibility, performance, reliability, and ease-of-use, the ATX form factor (including microATX and FlexATX) cannot be beat. ATX has several distinct performance and functional advantages over Baby-AT and is vastly superior to any proprietary designs, such as LPX. The once-popular NLX form factor has largely been replaced by FlexATX. The newest form factor, BTX, offers superior cooling but is more expensive than ATX and requires a new power supply and case design.

  • Built-in interfaces. Ideally, a motherboard should contain as many built-in standard controllers and interfaces as possible (except perhaps video). There is a trend toward legacy-free PCs that lack the conventional Super I/O component and therefore have only USB and sometimes IEEE 1394 for external expansion. Legacy-free PCs lack the conventional keyboard and mouse ports, serial and parallel ports, and possibly even the internal floppy controller. Systems that use an integrated Super I/O component have these interfaces.

    Built-in 10/100 or 10/100/1000 Ethernet network adapters are also handy, especially if you are using a cable modem or DSL connection to the Internet. A built-in sound card is a great feature, usually offering full Sound Blaster compatibility and functions, and possibly offering additional features such as 5.1 (six-channel) or 7.1 (eight-channel) surround sound and SPDIF connections to a home theater system. If your sound needs are more demanding, you might find the built-in solutions less desirable, and you might want to have a separate sound card in your system. Built-in video adapters are also a bonus in some situations, but because there are many video chipset and adapter designs from which to choose, generally you'll find better choices in external local bus video adapters. This is especially true if you need the highest performance video available.

    Built-in devices usually can be disabled to allow future add-ons, but problems can result.

  • Onboard IDE interfaces. All motherboards on the market have included onboard IDE interfaces for some time now, but not all IDE interfaces are equal. Your motherboard should support at least UDMA/66 (ATA-66) speeds, which matches the best real-world performance currently available from IDE drives. UDMA/66, UDMA/100, and UDMA/133 actually exceed the real-world performance of current drives using these standards and thus provide you with headroom for future drives. For even greater speed, consider motherboards with onboard IDE RAID controllers. These motherboards can be configured to perform data striping for extra speed or data mirroring for extra reliability when two or more identical IDE drives are used. These motherboards are based on a variety of standard chipsets with RAID functions added by RAID chipsets from AMI, HighPoint, or Promise. Many recent systems now include Serial ATA drive interfaces, some of which include RAID functions. SATA is even faster than ATA-133 and exceeds the real-world performance of current (first-generation) SATA drives by a wide margin.

    Tip

    With a never-ending stream of motherboards coming onto the market, finding motherboards with the features you want can be difficult. Motherboard Homeworld's Mobot search engine helps you find motherboards based on your choice of form factor, platform, chipset, CPU type, processor, manufacturer, memory type, slot types, built-on ports, and more. Check it out at www.motherboards.org/mobot/.


  • Power management. The motherboard should fully support the latest standard for power management, which is ACPI. An Energy Starcompliant system is also a bonus because it uses less than 30 watts of electrical energy when in sleep mode, saving energy as well as your electric bill.

  • Documentation. Good technical documentation is a requirement. Documents should include information on any and all jumpers and switches found on the board, connector pinouts for all connectors, specifications for other plug-in components, and any other applicable technical information. Most vendors provide this information in electronic form (using the Adobe Reader PDF format) on their websites , so you can preview the information available for a given motherboard before you buy.

  • Technical support. Good online technical support goes beyond documentation. It includes driver and BIOS updates, FAQs, updated tables of processor and memory compatibility, and utility programs to help you monitor the condition of your system. In addition to these online support features, make sure the vendor can be contacted through email and by phone.

You might notice that these selection criteria seem fairly strict and might disqualify many motherboards on the market, including what you already have in your system! These criteria will, however, guarantee you the highest-quality motherboard offering the latest in PC technology that will be upgradeable, be expandable, and provide good service for many years .

Most of the time I recommend purchasing boards from better-known motherboard manufacturers such as Intel, Acer, ABIT, AsusTek, SuperMicro, Tyan, FIC, and others. These boards might cost a little more, but there is some safety in the more well-known brands. That is, the more boards they sell, the more likely that any problems will have been discovered by others and solved long before you get yours. Also, if service or support is necessary, the larger vendors are more likely to be around in the long run.

Documentation

As mentioned, documentation is an important factor to consider when you're planning to purchase a motherboard. Most motherboard manufacturers design their boards around a particular chipset, which actually counts as the bulk of the motherboard circuitry . Many manufacturers, such as Intel, VIA, ALi, SiS, and others, offer chipsets. I recommend obtaining the data book or other technical documentation on the chipset directly from the chipset manufacturer.

For example, one of the more common questions I hear about a system relates to the BIOS Setup program. People want to know what the "Advanced Chipset Setup" features mean and what the effects of changing them will be. Often they go to the BIOS manufacturer thinking that the BIOS documentation will offer help. Usually, however, people find that there is no real coverage of what the chipset setup features are in the BIOS documentation. You will find this information in the data book provided by the chipset manufacturer. Although these books are meant to be read by the engineers who design the boards, they contain all the detailed information about the chipset's features, especially those that might be adjustable. With the chipset data book, you will have an explanation of all the controls in the Advanced Chipset Setup section of the BIOS Setup program.

Besides the main chipset data books, I also recommend collecting any data books on the other major chips in the system. This includes any floppy or IDE controller chips, Super I/O chips, and of course the main processor. You will find an incredible amount of information on these components in the data books.

Caution

Most chipset manufacturers make a particular chip for only a short time, rapidly superseding it with an improved or changed version. The data books are available only during the time the chip is being manufactured, so if you wait too long, you will find that such documents might no longer be available. The time to collect documentation on your motherboard is now !


Using Correct Speed-Rated Parts

Some vendors use substandard parts in their systems to save money. Because the CPU is one of the most expensive components on the motherboard and motherboards are sold to system assemblers without the CPU installed, it is tempting for the assembler to install a CPU rated for less than the actual operating speed. A system could be sold as a 2.4GHz system, for example, but when you look under the hood, you might find it's rated for only 2GHz. This is called overclocking , and many vendors have practiced this over the last few years. Some even go so far as to re-mark the CPUs, so that even if you look, the part appears to have the correct rating. The best way to stop this is to purchase systems from known, reliable vendors and purchase processors from distributors that are closely connected with the manufacturer. Overclocking is fine if you want to do it yourself and understand the risks, but when I purchase a new system, I expect that all the parts included will be rated to run at the speed to which they are set.

See "Processor Speed Ratings," p. 51.


When a chip is run at a speed higher than it is rated for, it runs hotter than it would normally. This can cause the chip to occasionally overheat, which would appear as random lockups, glitches, and frustration. I highly recommend that you check to ensure you are getting the right speed-rated parts you are paying for.

Also be sure to use the recommended heatsink thermal interface material (TIM). This can improve the efficiency of your heatsink by up to 30%.

This practice is easy to fall into because the faster-rated chips cost more money. Intel and other chip manufacturers usually rate their chips very conservatively. Over the years, I have overclocked many processors, running them sometimes well beyond their rated speeds. Although I might purchase a Pentium 4 2.4GHz and run it at 2.6GHz, if I were to experience lockups or glitches in operation, I would immediately return it to the original speed and retest. If I purchase a 2.6GHz system from a vendor, I fully expect it to have a 2.6GHz part, not slower parts running past their rated speeds!

Overclocking has been made more difficult by Intel and AMD, who have both started locking the bus multipliers in their chips to prevent easy overclocking by changing the multiplier setting on the motherboard. This is done mainly to combat re-marking CPUs and deceiving customers, although it unfortunately can also prevent those who want to from hotrodding their chips. Still, you can overclock most chips by increasing the CPU bus (front-side bus) speed within certain tolerances. Many of the motherboards on the market have tweakable CPU bus speeds specifically designed to allow overclocking. Check with your motherboard manual, or download the documentation from the manufacturer's website. You might find that your board is capable of things you didn't realize.

If you purchase a processor or system, verify that the markings are the original Intel or AMD markings and that the speed rating on the chip is what you really paid for.

The bottom line: If the price is too good to be true, ask before you buy. Are the parts really manufacturer-rated for the system speed?

To determine the rated speed of a CPU chip, look at the writing on the chip. Refer to Chapter 3 for details on how to interpret the marks to see what the rating on the chip actually is.

Caution

Be careful when running software to detect processor speed. Most programs can only estimate at what speed the chip is currently running, not what the true original rating is. The current speed of the processor might not be its actual rated speed, either because of overclocking or because some recent systems reduce processor speed when the system is not heavily tasked. One exception to this is the Intel Processor Frequency ID Utility, which can determine whether an Intel processor is operating at the correct and rated frequency intended. Although it gives only basic information about any Intel processor, it can uniquely identify the original speed ratings of the Pentium III, third-generation Celeron (Coppermine-based), and any newer processors, accurately determining whether they have been overclocked. For Pentium 4 and later processors, use the Intel Processor Identification Utility. Both are available from support.intel.com/support/processors/tools/piu/.

For AMD processors, use the AMD CPUInfo and AMDClock utilities to identify your processor type and speed. Download these and other utilities from http://www.amd.com/usen/Processors/TechnicalResources/0,,30_182_871_2364,00.html.

Older system chassis with speed markings or even indicator lights are usually no indication of the actual or rated speed of the processor inside. Those displays can literally be set via jumpers to read any speed you desire ! They have no true relation to actual system speed.

Most of the better diagnostics on the market, such as Norton Utilities from Symantec or SiSoftware Sandra, read the processor ID and stepping information, as well as show current operating (but not rated) speed. You can consult the processor manufacturer or Chapter 3 for tables listing the various processor steppings to see exactly how yours stacks up.