3. Buying the Basics

3.1. Things to Not Care About

An effect of PC commoditization is that there aren lots of things you used to have to worry about that don't matter any more, because the market has completely flattened out. We list these here to get them out of the way.

3.1.2. Memory

Judging the memory-controller and cache design used to be one of the trickiest parts of evaluating a motherboard, but that stuff is all baked into the processor itself now. This removed a large source of latency and design variations. It also killed off the plethora of different RAM types that used to be out there.

Today's advice is very simple. Make sure the memory is rated for your machine's bus speed, then buy as much as you can afford to stuff in your machine.

DDR3 RAM is beginning to appear. Right now its extra expense over DDR2 is not worth paying, for all but extremely specialized needs. It is almost always far more useful to have 4GB of reasonably fast RAM, than 2GB of very fast RAM, in your machine.

For more technical stuff on memory architectures, see The Ultimate Memory Guide maintained by Kingston Technologies.

3.2. How To Pick Your Processor

Right now (early 2010), the chips to consider for running Unix are the the 64-bit AMD Opteron or its Intel equivalents, especially the Core 2 Duo. We're long past the point at which 32-bit chips are interesting for new desktop systems, presuming you could even find one. AMD and Intel built up a buffer before switching their fabs fully to 64-bit chips in 2006, and the 32-bit chips you can still find are coming out of warehouses rather than off production lines.

Brands don't matter much, so don't feel you need to pay Intel's premiums if you see an attractive Cyrix, AMD or other chip-clone system offered. In the last few years I've been a big fan of the AMD line. They used to be faster, cheaper, and better-designed than Intel processors; today Intel has clawed back the speed advantage, but AMD chips still deliver more performance than you're likely to be able to use and do it with lower power dissipation (thus, less noise and heat).

On the other hand, Intel-chip motherboards now have the advantage that the on-board graphics chip will give you 3D acceleration with fully open-source drivers. This will avoid the problems you would otherwise face trying to select a supported graphics card from ATI or Nvidia.

Many CPUs now are multi-core — that is, they have multiple CPUs on a single chip. This is very useful for doing something compute intensive (re-encoding video, compressing large archives, etc.) in the background and still having a responsive system for other work at the same time. At current prices, a dual-core CPU makes good sense for most desktop systems. If you are building a server or have specialized computing needs you expect to be very CPU-intensive quad-core is worth considering, but on a desktop system all the two extra cores will usually do is emit heat. Only at the very low end (sub US$50 CPUs) do single-core CPUs still make sense on desktop machines.

Mainstream desktop CPUs now use one of two sockets: LGA 775 (Intel) and AM2 (AMD). Buying a system that uses one of these stands more chance of allowing a useful CPU upgrade to extend its useful life than systems using other less common sockets.

Current CPUs are much faster than those of just a few years ago. As a result, unless your needs are highly specialized, spending more than about US$200 on a desktop CPU is hard to justify. For most users, putting extra budget into more RAM or a faster disk subsystem will most likely result in greater benefit.

3.3. One Disk or Two?

I usually build with two disks — one "system" disk and one "home" disk. There are two good reasons to do this that have nothing to do with the extra capacity. One of them is the performance advantage of being able to interleave commands to different physical spindles that we'll explain a bit later in the section on disks. The other is that I am quite a bit less likely to lose two disks at once than I am to trash a single one.

Let's suppose you have a fatal disk crash. If you have only one disk, goodbye Charlie. If you have two, maybe the crashed one was your system disk, in which case you can buy another and mess around with a new Linux installation knowing your personal files are safe. Or maybe it was your home disk; in that case, you can still run and do recovery stuff and basic Net communications until you can buy another home disk and restore it from backups (you did keep backups, right?).

Given today's high capacity drives, another way to use two disks well is to set them up as a RAID1 (mirrored) array. This can be done in software or with a hardware RAID controller. This way if either of the two drives fail, the system will continue to function, no data is lost, and upon replacing the failed drive, the array can be rebuilt from the remaining working drive. Hard drives are consumable media, they do fail, so this approach (as well as good backups) is well worth considering.

Buy SATA. The older IDE and EIDE buses are now obsolete, and SCSI no longer has enough of a cost advantage to justify the premium. In fact, SCSI has effectively nerged into SCSI; SATA is SCSI commands being shipped over a single-wire data line.

3.4. Getting Down to Cases

I used to say that cases are just bent metal, and that it doesn't much matter who makes those. Unfortunately, this isn't true any more. Processors run so hot these days that fans and airflow are a serious concern. They need to be well designed for proper airflow throughout.

Look for the following quality features:

• Aluminum rather than steel. It's lighter and conducts heat better.

• Unobstructed air intake with at least one fan each (in addition to the power supply and processor fans)

• No sharp metal edges. You don't want to shred your hands when you're tinkering with things.

• There shouldn't be any hot spots (poor air flow).

• Sturdy card clips. Some poorly-designed cases allow cards to wiggle out of their slots under normal vibration.

• Effective and easy to use mechanisms for attaching hard drives, CD-ROM, CD-R/W, DVDs, etc.

If you're fussy about RFI (Radio-Frequency Interference), it's worth finding out whether the plastic parts of the case have conductive coating on the inside; that will cut down emissions significantly, but a few cheap cases omit it.

Should you buy a desktop or tower case? Our advice is go with tower unless you're building a no-expansions personal system and expect to be using the floppies a lot. Many vendors charge nothing extra for a tower case, and the cost difference will be trivial even if they do. What you get for that is less desktop clutter, more and bigger bays for expansion, and often (perhaps most importantly) a beefed-up power-supply and fan. Putting the box and its fan under a table is good for maybe 5db off the effective noise level, too. Airflow is also an issue; if the peripheral bays are less cramped, you get better cooling. Be prepared to buy extension cables for your keyboard and monitor, though; vendors almost never include enough flex.

The airflow thing is a good argument for a full- or mid-tower rather than the ‘baby tower’ cases some vendors offer. However, smaller towers are getting more attractive as boards and devices shrink and more functions migrate onto the motherboard. A state of the art system, with all 3" disks, 300W power supply, half-size motherboard, on-board SATA and 4GB of RAM sockets, and half-sized expansion cards, will fit into a baby or midsized tower with ample room for expansion; and the whole thing will fit under a desk and make less noise than a classic tower.

For users with really heavy expandability requirements, rackmount PC cases do exist (ask prospective vendors). Typically a rackmount case will have pretty much the same functionality as an ordinary PC case. But, you can then buy drive racks (complete with power supply), etc. to expand into. Also, you can buy passive backplanes with up to 20 or so slots. You can either put a CPU card in one of the slots, or connect it to an ordinary motherboard through one of the slots.

Since USB has taken over most forms of detachable peripheral, a good feature to look for in a case is USB ports mounted at the top forward edge where it's easy to plug in digital cameras and the like.

3.5. Power Supplies and Fans

A lot of people treat power supplies as a commodity, so many interchangeable silver bricks. We know better — cheap power supplies go bad, and when they go bad they have a nasty habit of taking out the delicate electronics they're feeding. Also, the power supply tends to be the noisiest component in your system.

Give preference to supplies with a Underwriter's Laboratories rating. There's some controversy over optimum wattage level. On the one hand, you want enough wattage for expansion. On the other, big supplies are noisier, and if you draw too little current for the rating the delivered voltage can become unstable. And the expected wattage load from peripherals is dropping steadily. On the other hand, processors and their cooling fans eat a lot more power than they used to.

The choice is generally between 200W and 300W. After some years of deprecating 300W-and-up supplies as overkill, I'm now persuaded it's time to go back to them; a modern processor can consume 50-75W by itself, and for the newer dual-processor board the power supply needs to be rated 450W or up.

Processors on modern motherboards run hot enough that all vendors have gone to embedded temperature sensors and variable-speed thermostat-controlled fans, out sheer self-defense (this used to be a high-end only feature).

To cut noise, look for 120mm fans rather than the old-style 80mm muffin fans. These can move the same amount of air per minute rotating at a lower tip speed, which means less vortex formation and less noise. These are now becoming standard even on cheap white-box hardware.

In garden-variety tower cases there often isn't enough airflow to cool all components effectively with a single fan, even going at full speed. And the single fan in the power supply was basically designed to cool the power supply, not the components in the case. This is why processors and some graphics cards have their own fans now.

A few years ago PCs often had two or more case fans in addition to the power-supply fan. This made sense in the era of 80mm fans and lots of expansion cards obstructing the airflow, but it was noisy. Nowadays, with sound and graphics and Ethernet integrated onto motherboards, expansion cards are much less common (and processors carry their own mini-fans). Thus, today's standard is to mount one 120mm fan, usually low and forward just beneath the disk-drive stack. This is much quieter, like by a factor of three or four.

The noise produced by a fan is not just a function of the speed with which it turns. It also depends on the nature of the airflow produced by the fan blades and the bearings of the rotor. If the blades cause lots of turbulent airflow, the fan produces lots of noise. One brand of fans that is much more silent than most others even if going at full throttle is Papst.

3.6. Motherboards

Provided you exercise a little prudence and stay out of the price basement, motherboards and BIOS chips don't vary much in quality. There are only six or so major brands of motherboard inside all those cases and they're pretty much interchangeable; brand premiums are low to nonexistent and cost is strictly tied to maximum speed and bus type. There are only four major brands of BIOS chip (AMI, Phoenix, Mylex, Award) and not much to choose between 'em but the look of the self-test screens (even the "name" vendors use lightly customized versions of these). One advantage Unix buyers have is that Unixes are built not to rely on the BIOS code (because it can't be used in protected mode without more pain than than it's worth). If your BIOS will boot properly, you're usually going to be OK.

Some good features to look for in a motherboard include:

• Gold-plated contacts in the expansion slots and RAM sockets. Base-metal contacts tend to grow an oxidation layer which can cause intermittent connection faults that look like bad RAM chips or boards. (This is why, if your hardware starts flaking out, one of the first things to do is jiggle or remove the boards and reseat them, and press down on the RAM chips to reseat them as well —this may break up the oxidation layer. If this doesn't work, rubbing what contacts you can reach with a soft eraser is a good fast way to remove the oxidation film. Beware, some hard erasers, including many pencil erasers, can strip off the plating, too!)

• The board should be speed-rated as high as your processor, of course. It's good if it's rated higher, so upgrade to a faster processor is just a matter of dropping in the chip and a new crystal.

(I used to have "Voltage, temperature and fan speed monitoring hardware." on this list. But processors run so hot nowadays that all current motherboards have it.)

The dominant form factor is still ATX. Intel tried to replace it with a new standard called BTX in late 2004-2005, but failed; the proposal was effectively withdrawn in 2006. In January 2007 AMD announced a DTX specification for small-form-factor PCs; it seems also to have sunk without trace.

3.7. Monitor and Video

The largest user-visible change since the last major update of this guide is that the CRT (cathode-ray tube) is dead. The manufacturers shut down their production lines in late 2004; the remaining CRTs out there are old stock that's been sitting in warehouses. The only reason to buy one since then has been to get high-end resolution at a price lower than the insanely expensive high-end flatscreens; with 1920x1440 flatscreens having become generally available at reasonable prices even that reason is gone. It's all flatscreens now, baby.

On flatscreens, only two statistics matter; pixel size and response time. The biggest functional drawback of flatscreens relative to CRTs is that they refresh more slowly, because cheical reactions in a flatscreen pixel take longer than remodulating a flying electron beam. You'll never notice this during ordinary desktop use, but it can cause streakiness and artifacts when you're playing games or viewing movies. If you're going to do that a lot, the price premium for a flatscreen with better response time may be worth it.

Next, buy your card (if you have to; see next paragraph). This used to be complicated, with issues like matching the video bandwidths of the card and the CRT, and the amount of display memory. Now (unless you are a gamer or have similarly extreme 3D acceleration requirements) it's simple; all cards have enough display memory for every resolution in use, and the issues are software (does it have an open-source driver, and do you care?)

It's actually fairly likely you'll never buy a video card again. Very capable graphics chips are routinely integrated onto motherboards now; unless you're a gamer or somebody else who absolutely must have the latest wheeze in 3D acceleration, they'll be good enough. Even this is not a stable situation, as 3D acceleration is commoditizing too.

I used to carry a lot of material on different video standards, interlacing, and flicker. That stuff is all obsolete now.

Here's what to look for on the monitor spec sheet:

• Screen size and format. Usually measured in diagonal inches. Most displays are now in a "widescreen" format (16:10 ratio of width:height) rather than the older 5:4 or 4:3 ratios common for CRTs and older flat panel screens. A "19 inch" widescreen monitor generally has considerably fewer pixels than a "19 inch" 5:4 ratio one. Unfortunately, this chane is bad for pogrammers, as it tends to lose us the vertical pixel resolution we want for editor windows.

• Screen resolution. 1280x1024 is now low end on the desktop. Seventeen inch 1280x1024 screens are the bargain basement now, many manufacturers have already switched production to 19 inch widescreen 1440x900 screens instead. The cost difference between such screens and 20 inch 1680x1050 screens is very small, making the 20 inch screens a better choice unless funds (or desktop space!) are very tight.

• 5ms or lower response time. 3ms is better. There is some marketing-speak going on in the way the response time is specified (grey to gray rather than black to white) but since most manufacturers do it this way these times are usually comparable between different manufacturers screens.

• Does it have a tilt-and-swivel base? Adequate controls, including both horizontal and vertical size and horizontal and vertical centering? A color-temperature control is a plus; the last is particularly important if you compose graphics on screen for hardcopy from a printer.

If you can, buy your monitor from someplace that will let you see the same monitor (the very unit you will walk out the door with, not a different or `demo' unit of the same model) that will be on your system. There's significant quality variation (even in "premium" monitor brands) even among monitors of the same make and model.

3.8. DVD Drives

DVD drives have two main uses in computer systems: playback of video DVDs, and use for data storage (either installation media or backups, or even as a primary drive in a few specialized systems).

DVD video playback used to be problematic on Unix due to various stupid copy-protection schemes in firmware, but they have long since been cracked. These days, any SATA DVD will do fine.

DVD burners (drives that can read and write CDROM media as well as several kinds of DVD media) are now low cost and useful. The SATA interface has taken over here, too. Linux and most current PC Unix-like systems will work fine with either interface, which is good as most PCs now ship with one.

3.9. Sound Cards and Speakers

You can't buy a really bad sound card any more. Even low-end sound cards or the sound chips embedded in a lot of PC motherboards these days support support all these features:

• 16-bit sampling (for 65536 dynamic levels rather than 256).

• Mono and stereo support.

• Full-duplex mode.

• Sampling rate of 44.1KHz (CD-quality).

• MIDI interface via a standard 15-pin D-shell connector.

• RCA output jacks for headphones or speakers.

• A microphone jack for sound input.

If you are interested in multi-track digital recording, two particularly good choices are the M-Audio Delta, or RME Hammerfall series of cards. Decent (and lower cost!) two-channel cards for more normal use are those using the ICE1712 (Envy24) and ICE1724 (Envy24HT) audio chips. For normal users, though, the on-motherboard chips will work fine.

A rather comprehensive list of sound cards and chips supported by the ALSA project, which is the main way sound cards are supported under Linux, can be found at ALSA Sound Card Matrix.

In speakers, look for a magnetically-shielded enclosure with volume, bass and treble controls. Some speakers run off the card's 4-watt signal; others are "self-powered", using batteries or a separate power supply. Your major buying choice is which one of these options to pursue. Usually you'll want separately-powered speakers. If appropriate for your listening habits, a pair of decent headphones will get you better quality sound for the money compared to speakers.

One final, important tip: that audio cable from your CD-ROM back to the sound card is used only when you play audio CD-ROMs through your speakers. Software-generated sound goes through the system bus, so you can play games with sound even if your sound board or motherboard won't accept the audio cable connector.

3.10. Modems

Demand for (dialup telephone) modems is dropping as more and more people get broadband Internet through DSL and cable. This section still has as much detail as it does only because (a) there are people out beyond the exurbs who can't get broadband, and (b) there are one or two remaining traps for the unwary.

The modem market has stabilized and standardized. If you can spend $59, get a U.S. Robotics V.92 USB external. You can then know that you've got the best and skip the rest of this section. If you really must economize, spend $39 for the internal-card version (but you'll probably regret the $20 first time you have to do diagnostics).

If you live somewhere with really bad telephone lines, the U.S. Robotics V.92 Business Modem may be truly "the best" for your needs, though it is about four times the price of the U.S. Robotics V.92 USB external, which is marketed for home use. See the U.S. Robotics web site for current product numbers and more detailed specifications.

The modem market is like consumer electronics (and unlike the computer market as a whole) in that price is a very poor predictor of performance. For ordinary file transfers, some $50 modems are better than some $150 modems. Paying top dollar mainly buys you better tolerance of poor connections and better performance at heavy-duty bi-directional transfers (such as you would generate, for exmaple, using SLIP or PPP over a leased line to an Internet provider).

In today's market all modems do a nominal 56kbps —V.90 and V.92 plus V.29 or V.17 fax transmission and reception (over plain old phone lines you won't get more than 53K of that). You don't see much in the way of slow/cheap to fast/expensive product ranges within a single brand, because competition is fierce and for many modem board designs (those featuring DSP (Digital Signal Processor) chips run by a program in ROM) adding a new protocol is basically a software change.

3.11. Printers

The most important thing to optimize nowadays is cost of consumables. Printer manufacturers, especially at the low end, have adopted a model under which they sell printers with near-zero or even negative margin, then gouge you horribly on the cost of cartridges and ink. Common tactics include (a) shipping half-filled "starter" cartridges with your printer, so you have to replace much sooner than you'd think, (b) toner-empty sensors deliberately miscalibrated to blink the error light on your printer when they're still a quarter to a third full, and (c) electronic countermeasures to lock out cheap third-party refills - in one notorious case, a printer manufacturer used the DMCA to sue refill vebdoers who circumvented these!

Better dealers (the Staples chain, for example) will show you a chart covering price and consumable-cost-per-page for all the models they carry. If you don't see this, leave. When you do, estimate your monthly print volume and trade off up-front against consumables price. appropriately. Hint: The vendors count on you underestimating your volume and consumables cost, and you usually will. Payiing a few extra bucks up front to lower that cost is smart.

Other than that, there really isn't all that much to be said about printers; the market is thoroughly commoditized and printer capabilities pretty much independent of the rest of your hardware. The PC-clone magazines will tell you what you need to know about print quality, speed, features, etc. The business users they feed on are obsessed with all these things.

(There used to be a problem with "GDI printers" and "WinPrinters" that only worked with Windows —they required special drivers that took over your CPU to do image processing, These were such a bad idea that they have basically disappeared off the market.)

Most popular printers are supported by GhostScript, and so it's easy to make them do PostScript. If you're buying any letter-quality printer (laser or ink-jet), check to see if it's on GhostScript's supported device list — otherwise you'll have to pay a premium for Postscript capability! Postscript is still high-end in the Windows market, but it's ubiquitous in the Unix world.

Warning, however: if you're using ghostscript on a non-Postscript printer, printspeed will be slow, especially with a serial printer. A bitmapped 600 dpi page has a lot of pixels on it. At today's prices, paying the small premium for Postscript capability makes sense.

If you're buying a printer for home, an inkjet is a good choice because it doesn't use gobs of power and you won't have the toner/ozone/noise/etc mess that you do with a laser. If all you want is plain-ASCII, dot-matrix is cheaper to buy and run — if you can find one. Inexpensive ink-jets and lasers have almost driven them off the market.

Inkjets are great in that they're cheap, many of them do color, and there are many kinds which aren't PCL but are understood by Ghostscript anyway. If you print very infrequently (less than weekly, say), you should be careful to buy a printer whose print head gets replaced with every ink cartrige: infrequent use can lead to the drying of the ink, both in the ink cartrige and in the print head. The print heads you don't replace with the cartrige tend to cost nearly as much as the printer (~$200 for an Epson Stylus 800) once the warranty runs out (the third such repair, just after the warranty expired, totalled one informant's Stylus 800). Be careful, check print head replacement costs ahead of time, and run at least a cleaning cycle if you don't actually print anything in a given week. (Conversely, toner starts out dry, and ribbon ink won't evaporate for years...if you truly print only rarely, but neither a dot matrix nor a laser makes sense, consider buying no printer and taking your PostScript files to a copy shop...)

Nowadays, a lot of printers are moving away from parallel-port interfaces to USB. This is a good idea, because USB devices announce themselves to the host computer and can be automatically configured. Parallel ports (and serial ports for that matter) are becoming obsolete. Many new PC motherboards no longer include them.

Many printers (even some sub-$100 models) now come with a network (10/100 Ethernet) interface. This make sharing them trivial, and also avoids having to leave a desktop PC powered on so others (using notebooks perhaps) can print to your printer. Therefore, such printers are worth considering in many networked environments, including home networks.

In the near future, new motherboards may stop including parallel and serial ports altogether. That's another good reason to go with a USB- or Ethernet-capable printer.

3.12. Power Protection

I strongly recommend that you buy a UPS to protect your hardware and data. MOV-filtered power bars make nice fuses (they're cheap to replace), but they're not enough. I have written a UPS HOWTO that provides more complete coverage of what used to be in this section.

3.13. Radio Frequency Interference

(Thanks to Robert Corbett <Robert.Corbett@Eng.Sun.COM> for contributing much of this section)

Radio Frequency Interference (RFI) is a growing problem with PC-class machines. Today's processor speeds are such that the electromagnetic noise generated by a PC's circuitry in normal operation can degrade or jam radio and TV reception in the neighborhood. Such noise is called Radio Frequency Interference (RFI). Computers, as transmitting devices, are regulated by the Federal Communications Commission (FCC).

FCC regulations recognize two classes of computer:

If a PC is to be used in a home or apartment, it must be certified to be FCC class B. If it is not, neighbors have a legal right to prevent its use. FCC class A equipment is allowed in industrial environments.

Many systems are not FCC class B. Some manufacturers build boxes that are class B and then ship them with class A monitors or external disk drives. Even the cables can be a source of RFI.

It pays to be cautious. For example, the Mag MX17F is FCC class B. There are less expensive versions of the MX17 that are not. The Mag MX17 is a great monitor. It would be painful to own one and not be allowed to use it.

An upgradeable system poses special problems. A system that is FCC class B with a 33 MHz CPU might not be when the CPU is upgraded to a 50 or 66 MHz CPU. Some upgrades require knockouts in the case to be removed. If a knockout is larger than whatever replaces it, RFI can leak out through the gap. Grounded metal shims can eliminate the leaks.

Even Class B systems don't mix well with wireless phonesets (not cellular phones, but the kind with a base station and antennaed headset). You'll often find a wireless phone hard to use withing 20 feet of a Class B machine.

To cut down on RFI, get a good metal case with tight joints, or at least make sure any plastic one you buy has a conductive lining. You can also strip the painted metal-to-metal contacting parts of paint so that there's good conductive metal contact. Paint's a poor conductor in most cases, so you can get some benefit from this.