D. J. Bernstein
Computer hardware

Advice for computer buyers

The standard workstation

If you ask me what computer to buy, I'll start by suggesting the standard workstation. It's a very nice x86 (Intel-compatible) computer: solid, very fast, and amazingly inexpensive.

Of course, the computer market moves quickly, so the details of the standard workstation are constantly changing. I occasionally update this page with details of the most recent standard workstation.

If you build a machine along these lines, send email to djb-hardware a few weeks later reporting the hardware details and the results.

The 2003.06.27 standard workstation

The 2003.06.27 standard workstation costs $473. Notes on the price: The standard workstation does not include a monitor, keyboard, or mouse.

A catalog might say that what you're getting for $473 is ``Athlon 2400+, 80GB, 256MB DDR, DVD, Ethernet, audio, video.'' I'd add ``built for reliability'': the motherboard, power supply, hard drive, drive cable, and memory are all from well-known manufacturers; the power supply, hard drive, and CPU are covered by 3-year warranties; the power supply is a big 350W; there are four case fans; and the memory is ECC.

The following tables show the components of the standard workstation in detail. You can visit these warehouses online, select these components from the warehouse catalogs, and have the components shipped to you in a few days. Prices can change at any moment; use Price Grabber to find the latest and greatest prices.

Warning: The AXDA2400BOX requires 7DXE revision 3.1 (or later) and BIOS version F4 (or later). Most warehouses fail to specify motherboard versions. GoogleGear, for example, refuses to confirm their 7DXE version; I've heard of them shipping revision 3.1, but you'll have no recourse if they decide to give you revision 2.0 instead. To protect yourself, order only from warehouses that confirm their 7DXE version, and save the confirmation before you place your order.

The following components are available from GoogleGear:
$85AMD AXDA2400BOX: 2000MHz PC2100 Socket-A Athlon XP Model 8 CPU with a fan3 years from AMD69?
$77Western Digital WD800JB: 80GB 7200RPM UATA hard drive3 years from Western Digital27 at +12V (for spinup), 4 at +5V
$35Artec DHM-G48: 16X DVD-ROM 40X CD-ROM drive1 year from Artec15 at +12V, 8 at +5V
$11D-Link DFE-530TX+ retail: 100Mbps network cardlifetime from D-Link5?
$0UPS 2-day shipping

The following components are available from AccuPC:
$59Gigabyte GA-7DXE version 3.1 BIOS F4: PC2100 Socket-A UATA 305mmx244mm motherboard with audio2 years from Gigabyte20?
$0FedEx Saver shipping

The following components are available from Ebuyer:
$85Antec SX835II: 11kg 440mmx472mmx206mm case with an SL350 power supply (max output watts: 2.5 at -5V; 9 at -12V; 330 at +5V, +3.3V, +12V combined; 230 at +5V, +3.3V combined; 175 at +5V; 192 at +12V; 92 at +3.3V) and two fans3 years from Antec5? for fans
$0UPS ground shipping
You may want to check local computer stores for the SX835II case. I've seen the case for about $60 plus tax.

The following components are available from Allstar:
$47Kingston KVR266X72C2/256: 256MB PC2100 ECC memory in one DIMMlifetime from Kingston4
$25Sapphire 1021-F106-0D-SA Rage 128 Pro: 32MB video card using ATI Rage 128 Ultra chip1 year from Allstarshop10?
$20two Vantec SF8025L: 80mm 27CFM 21db double-ball-bearing fanslifetime from Vantec2 each
$10UPS ground shipping

The following components are available from Essential Computers:
$13Cooler Master UTC-A24: grounded round 24-inch UATA cable
$6FedEx 2-day shipping

Variant: better low-end components

The DVD drive was selected entirely on the basis of price. If you want to write CDs, upgrade to a DVD/CD-RW drive for about $30 more.

The network card and video card were selected almost entirely on the basis of price, but with the extra constraint of UNIX compatibility. The DFE-530TX+ and ATI Rage 128 have been around for a while and are widely reported to work without trouble. (The FA311 and FA312 network cards are also well supported by UNIX, but they don't work with AMD-761-based motherboards such as the 7DXE.)

If you're building a home computer, you may want a modem instead of, or in addition to, an Ethernet card. Beware that most internal modems are "WinModems" requiring OS support. Linux and FreeBSD can both use the Lucent LT modem chipset.

The standard workstation no longer includes a floppy drive. You can add a floppy drive if you have any use for one.

Variant: more memory

A Kingston KVR266X72C2/512 (512MB PC2100 ECC memory in one DIMM; 5 watts) is only $78.

You can put as many as three DIMMs into the 7DXE.

Variant: dual CPUs

A dual-CPU computer provides almost twice the performance of a single-CPU computer for parallelizable computations. It costs much more than simply an extra CPU, because the CPUs, motherboard, and power supply need to support dual processing.

For example, 2003.06.15 prices: Two 2000MHz Athlon MPs cost $158+$158 (including shipping) from GoogleGear, replacing a 2000MHz Athlon XP at $85. A Gigabyte GA-7DPXDW+ motherboard costs $200, replacing a 7DXE at $61 and a network card at $13. (The Asus A7M266-D/L motherboard is more highly recommended, but it doesn't seem to be sold anywhere.) An SL450 power supply is about $30 more expensive than an SL350 power supply.

Dual-CPU computers are sensible if you want the maximum possible power inside a single case; perhaps the standard workstation will be a dual-CPU computer someday. On the other hand, if you want the maximum possible computation power per dollar, you should buy separate stripped-down single-CPU computers.

(Note to computer manufacturers: You should think about putting two motherboards, and a fast network link between the motherboards, into one case. The crucial simplification is that each CPU has its own memory.)

Variant: different CPU speeds

You can buy a lower-speed CPU if you want to save money, or a higher-speed CPU if you want more power. I tend to avoid the highest-speed CPUs; two lower-speed CPUs give much better performance for a comparable price.

The following table indicates prices, including shipping, of Athlon XPs at different speeds. Prices are from various warehouses as reported by Price Grabber; usually GoogleGear has the best price. Prices are for "retail boxed" CPUs, i.e., CPUs and attached fans covered by a 3-year warranty. (In contrast, "OEM" CPUs don't include fans, and they have a shorter warranty. You have to buy and attach a separate fan.) Athlon model 10 (aka Barton) has 512KB L2 cache; Athlon models 8 (aka Thoroughbred) and 6 (Palomino) have 256KB L2 cache. PC2700 memory runs at 333MHz; PC2100 memory runs at 266MHz. Watch out for overlaps in the AMD part numbers.

Athlon model memory speed AMD part number CPU speed (MHz) 2003.06.15 price 2003.02.23 price
10PC2700AXDA 3000 BOX2167 $259
8PC2700AXDA 2700 BOX2167 $134 $281
8PC2100AXDA 2600 BOX2133 $251
10PC2700AXDA 2800 BOX2083 $177
8PC2700AXDA 2600 BOX2083 $101
8PC2100AXDA 2400 BOX2000 $85 $155
10PC2700AXDA 2600 BOX1917
10PC2700AXDA 2500 BOX1833 $92
8PC2100AXDA 2200 BOX1800 $76 $116
8PC2100AXDA 2100 BOX1733 $73 $101
6PC2100AXP 2100 BOX1733
8PC2100AXDA 2000 BOX1667 $67
6PC2100AXP 2000 BOX1667 $86
8PC2100AXDA 1900 BOX1600
6PC2100AXP 1900 BOX1600 $86
8PC2100AXDA 1800 BOX1533 $60 $72
6PC2100AXP 1800 BOX1533
8PC2100AXDA 1700 BOX1467 $69 $63
6PC2100AXP 1700 BOX1467
6PC2100AXP 1600 BOX1400
6PC2100AXP 1500 BOX1333

Beware that any motherboard has limits on the processors it can support. Sometimes a motherboard can support a processor after a software upgrade (a ``BIOS flash''). For example, the Gigabyte web pages say that the 7DXE version 2.0 supports ``up to Athlon XP 2200+'' (but only Model 6, not Model 8) with ``BIOS version F3 or later,'' while version 3.1 supports ``up to Athlon XP 2600+'' (but not the 2200+) with ``BIOS version F4 or later.''

Building a Pentium 4 system means changing CPU from the Athlon XP to a Pentium 4 and changing motherboard to a PC2100 Pentium 4 motherboard. I don't recommend this: it substantially reduces the computation power per dollar.

Variant: larger drives

If you have more money to spend, the hard drive is one of the most obvious places to spend it. You can buy a much larger drive (for example, the 180GB WD1800JB for $167); you can buy an external drive for backups; or you can buy several drives, and store data with parity using software RAID level 5. (Parity is an easy-to-use automatic backup mechanism: your latest data is still accessible even if a drive dies. Three disks with parity can store as much data as two disks without parity.)

Make sure you have enough cables for your drives. A typical motherboard, such as the 7DXE, can support four drives (two per cable): e.g., three hard drives and a DVD. An extra $30 UATA controller card can support four more drives. The SX835II case has room for eight drives.

(Cable quality is hard to assess, but the UTC-A24 appears to be the best cable available today. A low-quality cable can destroy data written to disk: UATA data signals use ECC, but UATA instruction signals don't.)

I generally opt for lower-RPM drives. Lower-RPM drives are less expensive; lower RPMs are less stressful, and therefore likely to last longer; and history suggests that lower-RPM models are much less likely to be badly manufactured than higher-RPM models. The performance difference (most importantly, the reduction in average seek time) is irrelevant: modern workstations have enough memory, so they rarely access their disks.

Extra disks are a much better choice than tapes for backups. Disks are much faster and much more reliable than tapes. Disks used to be substantially more expensive than tapes, but now they're about the same price.

Most of the drive manufacturers switched to 1-year warranties in October 2002; 3-year-warranty drives sold out within a few months. Exception: Western Digital is still offering 3-year warranties on its Special Edition Caviar (WD400JB, WD600JB, WD800JB, etc.) drives. So I've switched to those. (The 3-year warranty is standard, not an extended warranty. Western Digital doesn't offer a lower-cost 1-year-warranty option. Presumably this means that they don't expect many of these drives to fail within 3 years.)

Add-ons: video

The standard workstation doesn't include a monitor. You should buy a monitor if you don't already have one. On the other hand, if you have two or more computers in one room, you may instead want to buy a KVM (keyboard, video, mouse) switch so that all the computers can share one monitor. You may also want to buy a printer for high-resolution paper output, a scanner for high-resolution paper input, and a "webcam" for video input.

15" LCDs from various warehouses reached the magical price points of $299 in 2001 and $249 in 2003. For comparison, typical 17" CRT prices remained stable between $100 and $200. 15" LCDs are easier to read than 17" CRTs, are easier to move around, take less desk space, use less power, and will probably last a lot longer.

If you plan to do a lot of graphics work, you will want a larger monitor and perhaps a fancier video card.

Add-ons: audio

A typical motherboard (for example, the GA-7DXE) includes an audio chipset with three connectors on the back of the computer: Loudspeakers, headphones, and earbuds connect to the line-out jack. Microphones and computer headsets connect to the microphone jack. Phone headsets have a different plug and won't connect to anything.

You will probably want a pair of earphones (headphones or earbuds) for private sound; you may also want a pair of loudspeakers for public sound. I find earbuds much more comfortable than headphones for extended use. Don't bother with earphones that use ceramic (ceramic strontium ferrite) or alnico (aluminum nickel cobalt) magnets; neodymium (neodymium iron boron) magnets provide several times more energy product (BHmax), typically 30 MGOe rather than 5 MGOe, without making a big difference in overall cost. A tiny $10 pair of earphones with neodymium magnets, such as the Sony MDR-E828LP earbuds that I'm using right now, can reach extremely painful volume levels without noticeable sound distortion.

(Actually, the standard workstation includes a small internal speaker on the motherboard. It's possible to use the internal speaker for 5-bit mono 22KHz sound. However, this requires support that most operating systems don't provide. In practice, the internal speaker is used only for occasional beeps.)

Alternative: prebuilt computers

Instead of selecting the components you want for your computer, you can buy a computer built by HP, Compaq, Dell, etc. through warehouses such as PC Connection or Outpost.

Prebuilt computers have several differences from the standard workstation described above:

If you do buy a prebuilt computer, I recommend buying one with a 3-year warranty. For example, on 2003.02.27, for $509 plus shipping, Compaq is offering a ``D315'' computer with a 1667MHz Athlon XP, a 20GB drive (as compared to the standard workstation's 80GB drive), 128MB DDR memory (as compared to 256MB DDR error-correcting memory), a CD-ROM drive (as compared to CD+DVD), an Ethernet card, audio, video, keyboard, mouse, a floppy drive (not included in the standard workstation), Windows XP Home (not included in the standard workstation), and a 3-year warranty.

Alternative: non-x86 processors

I sometimes buy overpriced processors so that I can see exactly how fast they are. This does not mean that you should buy them. When I publish software with optimizations for a Pentium-90, a PowerPC G4-533, and an UltraSPARC IIe-500, I am trying to help people take advantage of the hardware they already have; I am not suggesting that more of this hardware should be produced.

Apple's 2003.02.15 and 2003.06.14 university price lists (Collegiate Purchase Program Price List) both showed a $1299 Power Mac G4 with a 1000MHz processor, 256MB non-ECC DDR memory, a 60GB hard drive, a video card, a DVD/CD-RW drive, a 10/100/1000 Ethernet card, a modem, a keyboard, and a mouse.

This Mac costs twice as much as the standard workstation and is much slower. Hint to Apple: You'd sell a lot more of your software if you stopped trying to use it as a tool to sell your overpriced hardware.

Similarly, between 2003.02 and 2003.06, Sun's university price list showed a $1025 Sun Blade 150 workstation with a 550MHz UltraSPARC IIi processor, 128MB memory, a 40GB hard drive, etc. Sure, it's a nice computer, but it's not nearly as fast as the standard workstation.