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Building the Perfect Budget PC, Part 2

by Robert Bruce Thompson and Barbara Fritchman Thompson


In our last article, we detailed our component selections for perfect AMD and Intel budget PCs. In this article, we'll actually build the AMD system. We chose the AMD system as our example because we're more concerned about Linux compatibility on this platform than on the Intel-based system. We've built many Intel systems similar to our budget Intel configuration, and we know that Linux has excellent support for embedded Intel video, audio, and LAN. This will be the first AMD/nForce system we've built to run Linux, so we wanted to verify that Linux supports the integrated peripherals properly. The Intel and AMD configurations both support Windows, of course.

We made some minor departures from our recommended configuration of this system, but none that significantly affect using it to illustrate the build. For example, we already had an OEM Sempron 2800+ processor and a compatible CPU cooler in our stockroom, so we used those rather than order the exact components listed in Part 1 of this article. Similarly, because we plan to use this system for multimedia encoding, we installed a larger hard drive and two 256MB DIMMs rather than just one. Of course, modifying configurations to suit a particular purpose is one of the best reasons for building your own PC, so we've simply taken our own advice.

Building the System

Assembling a budget system usually doesn't take long. If this is your first project, plan to spend an afternoon assembling the system. If you've built systems before, you'll probably have this one completed in an hour. Begin by getting all your tools and components together. Open all the boxes and check their contents against the packing lists. Once you're sure you have everything you need, prepare a well-lit work area. The kitchen table is traditional. Use a blanket or old towels to protect the surface.

Preparing the case and power supply

We chose the Antec SLK2650BQE case for this system. Like its more expensive cousins, the Sonata and Overture, the SLK2650BQE is painted black. Instead of the glossy Piano Black finish used on those cases, though, the SLK2650BQE has a nice matte black finish. If anything, the matte black finish is less likely to show fingerprints and dust than the shiny black finish of the more expensive cases.

Before you do anything else, make sure the power supply is set to use the proper voltage, as shown in Figure 1. The 350W power supply bundled with the Antec SLK2650BQE can be set using a sliding switch for the 115VAC used in the United States and elsewhere or the 230VAC used in most of Europe. Although Antec and other case manufacturers are careful to set the correct voltage for the locale where each case is shipped, we have occasionally seen power supplies (on non-Antec models) set incorrectly. If your local voltage is 115VAC and the power supply is set for 230VAC, no harm is done except that the system won't boot. But if your local voltage is 230VAC and the power supply is set for 115VAC, powering up the system instantly destroys all components in a shower of sparks.

Figure 1
Figure 1. Setting the input voltage to 115VAC

After you've verified the input voltage setting, place the case on the table, remove the two thumbscrews on the rear, and slide the left-hand side panel off, as shown in Figure 1. Because the Antec SLK2650BQE is a Thermally Advantaged Chassis (TAC), the side panel incorporates an air vent and duct--visible as the black shroud on the side panel--that is positioned directly above the processor when the side panel is in place.

Figure 2
Figure 2. The Antec SLK2650BQE case

The side panel vent is designed to cool hot-running Prescott-core Pentium 4 processors, but its presence certainly does no harm with the cooler-running AMD Sempron. (Because the ATX specification defines the general motherboard layout, the TAC vent and duct are also properly positioned to cool the AMD Sempron processor.)

To provide additional cooling airflow, it's possible to remove the TAC duct and install a standard supplemental case fan between the side panel and the duct. If we were building a system with one of the hottest-running Pentium 4 processors, such as the Model 570, we'd have installed a supplemental fan. That wasn't necessary for the Sempron.

The next step is to remove the generic ATX I/O template supplied with the case and replace it with the I/O template provided with the ASUS A7N8X-VM/400 motherboard. To do that, from the exterior of the case press gently along the edges of the original template until it snaps out. Then, working from inside the case, place the I/O template supplied with the motherboard into position and press gently along the edges until it snaps into place, as shown in Figure 3.

Figure 3
Figure 3. Pressing the I/O template into place

With the I/O template in place, temporarily lower the motherboard into position, as shown in Figure 4, to verify which of the chassis mounting holes correspond to motherboard mounting holes. The ASUS A7N8X-VM/400 has eight mounting holes. The Antec SLK2650BQE comes with four brass standoffs installed, two of which are correctly positioned for the ASUS A7N8X-VM/400. The remaining two installed standoffs are placed for full-size ATX motherboards, and so they are well off to one side of the motherboard position. You can leave those extra two standoffs installed or remove them, at your discretion.

Figure 4
Figure 4. Verifying mounting hole positions

After you locate the six empty chassis mounting holes that correspond to the motherboard mounting holes, thread brass standoffs into each of the six, using your fingers, pliers, or a 5mm nut driver. (The standoffs and other mounting hardware are located in a plastic bag in a storage compartment in the black plastic shroud that covers the expansion slot covers on the exterior rear of the case.) Do not overtighten the standoffs.

Before you proceed, verify that each motherboard mounting hole has a corresponding standoff installed and that no extra standoffs are installed.

Populating the motherboard

With the case prepared, the next step is to populate the motherboard by installing the processor and memory. It's much easier to do this before the motherboard is installed in the case. You're also less likely to damage the processor, the memory modules, or the motherboard itself if you keep the motherboard on a firm, flat surface while installing the processor and memory.

To begin, locate the processor socket and raise the ZIF (zero insertion force) lever to vertical, as shown in Figure 5. Make sure the lever comes to full vertical, or even a bit beyond.

Figure 5
Figure 5. Opening the ZIF lever on the processor socket

With the ZIF lever vertical, drop the Sempron processor into the socket. Make sure that the gold triangle on one corner of the processor is aligned with the corner of the socket where the ZIF lever attaches, as shown in Figure 6. The processor should just drop into place, without any pressure being applied. If it doesn't, move it around slightly to make sure the processor pins are aligned with the socket holes. If necessary, apply very slight pressure to make sure the processor seats fully.

Figure 6
Figure 6. Installing the processor

When you are sure the processor is fully seated in the socket, press the ZIF lever down until it locks into place, as shown in Figure 7. This locks the processor into the socket and makes electrical contact between the processor pins and the socket.

Figure 7
Figure 7. Locking the processor into the socket

We actually used an OEM Sempron processor that we happened to have on hand, rather than the retail-boxed Sempron we listed in Part 1 of this article. That meant we needed a CPU cooler. We found a Dynatron DC1206BM-L/610-P-Cu in the workroom that had been on the shelf for a while.

The fastest CPU listed on the box was the Athlon XP 2600+, so it seemed likely this cooler would be good enough for a Sempron 2400+. To verify that, we checked the AMD Sempron Thermal Solutions page and found that the DC1206BM-L/610-P-Cu is now rated for processors as fast as the Athlon XP 3200+ and Sempron 3000+, so it's easily good enough for a Sempron 2400+ (or for the Sempron 2800+ we actually used). The DC1206BM-L/610-P-Cu is an inexpensive cooler--$7.50 at NewEgg--but it's still more efficient and quieter than the stock cooler, so perhaps it's just as well we used it instead of the stock cooler.

The Dynatron cooler is physically similar to the stock CPU cooler supplied with retail-boxed Sempron processors, so you can use the same procedure we describe if you use the stock AMD cooler. To begin installing the CPU cooler, peel off the protective cover to expose the phase-change thermal pad, shown in Figure 8.

Figure 8
Figure 8. Exposing the phase-change thermal pad before installing the CPU cooler

AMD is very specific about which thermal compounds should be used with its processors (PDF file). For what AMD calls lidless processors--those in which the processor die is exposed--it recommends using a phase-change thermal pad rather than thermal grease. AMD also recommends against using silver-based thermal compounds, concerned that they may cause electrical shorts and damage to the processor and motherboard. Despite this advice, we would ordinarily have used silver-based thermal compound with our lidless Sempron, because we dislike phase-change pads. We decided to use the phase-change thermal pad because we were building this system for this article, but we'll probably replace the thermal pad with silver-based compound the next time we tear this system down.

Although we cannot contradict AMD recommendations, we will say that we've been using Antec Silver Thermal Compound for years on all types of processors without any problems. If you follow directions, the risk of damaging anything is vanishingly small. Silver-based compounds transfer heat more efficiently than do silicone-ceramic thermal compounds, which allow slower fan speeds and accordingly lower noise levels. Still, if you follow our advice and your processor burns down, don't blame us. If you want to play by the rules, use the thermal pad supplied with the retail-boxed Sempron.

A CPU cooler installs in only one orientation. Note the "step" on the left side of the CPU cooler base in Figure 8. That step fits a matching raised area on the socket itself. To install the CPU cooler, align it so that the step on the heat sink matches the corresponding raised area on the socket, and place the cooler into position. The CPU cooler is secured by a spring steel bracket with notches on each end that snap over corresponding tabs on the socket base.

Seating the first end of the bracket is easy, because there's no pressure on the bracket at that point. Seating the second end of the bracket requires significant pressure against the springiness of the bracket. Use a small flat-blade screwdriver, as shown in Figure 9, to snap the second end of the bracket into place.

Figure 9
Figure 9. Securing the CPU cooler

With the CPU secured, the next step is to connect the CPU cooler fan to the CPU fan power header, which is located near the processor socket corner where the ZIF lever connects. This cable uses a keyed three-pin connector. Align the connector with the key on connector body matching the key on the motherboard header and press the connector into place, as shown in Figure 10.

Figure 10
Figure 10. Connecting the CPU cooler fan to the motherboard power header

The final step in populating the motherboard is to install the memory modules. (Although we originally configured this system with one 256MB memory module, we intend to use this system for multimedia encoding, so we decided to install a second 256MB DIMM.) If you are installing only one memory module, insert it into the slot labeled DIMM 1.

To install the module, pivot the white plastic retainers at each end of the slot outward, orient the module with the keying notch aligned with the keying tab in the slot, and press the module firmly into place, as shown in Figure 11. As the module seats, the white plastic retaining tabs should pivot back up to vertical, locking the module into place. If not, pivot them into position manually.

Figure 11
Figure 11. Seating a memory module

Installing the motherboard

With the motherboard populated, the next step is to install it in the case. To do so, lower it gently into place, verifying one last time that each motherboard mounting hole has a corresponding standoff installed and that no extra standoffs are present. Carefully align the motherboard rear I/O panel with the I/O template, and slide the motherboard into position. The threaded portion of each brass standoff should be visible through the corresponding motherboard mounting hole, although you may have to apply slight pressure toward the rear of the case to force everything into alignment.

As you slide the motherboard into position, verify that none of the ports on the I/O panel are obstructed by the grounding tabs on the I/O template. Ordinarily it's possible to do this by sliding the motherboard into place with the rear edge tilted slightly downward and the front edge slightly upward. In this case, we found that no matter how we tilted the motherboard, the grounding tab for the Ethernet port protruded into the port opening. We used a small flat-blade screwdriver, as shown in Figure 12, to maintain slight pressure against the grounding tab while we slid the motherboard into place. (In extreme cases, you may need to use pliers to bend a grounding tab out of the way before positioning the motherboard.)

Figure 12
Figure 12. Ensuring the grounding tab clears the Ethernet port

Once you have the board positioned correctly, partially insert two screws to hold it in place. Use gentle pressure to force the motherboard mounting holes into alignment with the brass standoffs, and partially insert the remaining screws. Once all eight screws are aligned and started, tighten all of them finger-tight. To avoid possibly cracking the motherboard, do not apply too much torque to the motherboard mounting screws.

With the motherboard secured, the next step is to connect the front panel switch and indicator cables, as shown in Figure 13. Switch cables are not polarized and may be connected in either orientation. LED cables are polarized and should be connected with the ground wire (usually green or black) to the ground pin and signal wire (usually red or white) to the signal pin.

Figure 13
Figure 13. Connecting the front panel switch and LED cables

The next step is to connect the front panel USB cable. Intel has defined a standard 5X2 USB connector block, with one pin blocked for keying. Each USB port requires four wires: +5VDC (sometimes labeled Power), D- and D+ (the two USB signal wires), and Ground. The Antec SLK2650BQE case provides a front panel USB cable with a 5X2 keyed connector block, and the ASUS A7N8X-VM/400 provides a corresponding set of header pins. After checking the pinouts to verify that both the cable and header pins followed the Intel standard, we connected the front panel USB cable, as shown in Figure 14. Antec offers an optional adapter that converts the front panel USB connector block to individual connectors for those who use a motherboard with nonstandard USB header pins.

Figure 14
Figure 14. Connecting the front panel USB cables

The next step is to connect the ATX main power cable to the motherboard, as shown in Figure 15. Verify that the cable seats completely and that the latch snaps into place. Unlike Intel motherboards, all of which place the main power connector near the right front edge of the motherboard, this ASUS motherboard places the main power connector near the I/O panel at the rear of the motherboard. We dislike this placement, because it requires the unwieldy 20-wire main power cable to cross the motherboard, potentially interfering with the CPU cooling fan and other components. Make sure to route and secure the main power cable carefully to avoid its possibly fouling the CPU fan or rear case fan.

Figure 15
Figure 15. Connecting the the ATX main power cable

The final step is to connect the fan control cable from the power supply to the fan power header located adjacent to the main ATX power connector, as shown in Figure 16. Connecting this cable allows the system BIOS to monitor and control the speed of the power supply fan.

Figure 16
Figure 16. Connecting the fan controller cable

Installing drives

With the motherboard installed and connected, the next step is to install the optical drive and hard drive. Before you install the drive, verify the jumper settings. We plan to install the hard drive as the master device on the primary ATA channel and the optical drive as the master device on the secondary ATA channel.

The Seagate Barracuda hard drive was jumpered properly by default. The Lite-On CD burner was jumpered as a slave device, as many optical drives are by default. We used our needle-nose pliers to move the jumper from the slave pins to the master pins, as shown in Figure 17.

Figure 17
Figure 17. Setting a drive jumper

To mount the optical drive, choose a 5.25-inch drive bay and pop out the plastic bezel cover. We used the top bay because our system will sit on the floor and we wanted the optical drive as high as possible for easy access. If your system will sit on a desk, we recommend using the lowest bay, for the same reason.

Behind the bezel cover is a metal RF shield plate. Twist it back and forth until it snaps out. (Be careful not to cut yourself on the burrs that remain when the plate is removed.) Remove the drive rail that is affixed to the metal plate.

The Antec SLK2650BQE uses a clever tool-free method for mounting 5.25-inch drives, using only one rail per drive. The left side of the drive rests on a narrow shelf that supports it vertically. The single rail connects to the right side of the drive. Unlike most rails, this one doesn't require screws. Instead it uses a spring-steel bracket, each end of which fits a screw hole on the drive. When the bracket is relaxed, the tips are too close together to span the distance between the screw holes on the drive. Putting pressure on the bracket flattens it and spreads the distance between the tips, allowing them to snap into the drive screw holes. To mount the rail, place one bracket tip in a screw hole, and align the rail along the bottom of the drive, parallel to the edge. Press down firmly with both thumbs, as shown in Figure 18, until the second bracket tip snaps into the second screw hole.

Figure 18
Figure 18. Seating a drive rail

To install the drive in the bay, first move the black plastic lock mechanism (visible in Figure 19) to the unlocked position. Connect an ATA cable to the rear of the drive, making sure that Pin 1 on the cable, the side with the red stripe, corresponds to Pin 1 on the drive, the side nearest the power connector.

Most ATA cables have three connectors. The blue connector on one end of the cable connects to the motherboard. The two device connectors are gray, in the middle, and black, at the other end. Some cables do not have colored connectors. In that case, the two connectors closest to each other are the device connectors.

Feed the slack end of the ATA cable through the drive bay to the inside of the case, and then slide the drive into position in the bay. With the drive fully seated, slide the lock mechanism to the locked position, as shown in Figure 19. Connect one of the peripheral power connectors from the power supply to the drive.

Figure 19
Figure 19. Securing the optical drive

To install the hard drive, begin by removing the hard drive bay, as shown in Figure 20. Slide the chrome locking lever to the rear, unlocked position, and slide the hard drive bay toward the rear of the case until it releases. We had to apply significant pressure to release the bay. Make sure the locking lever is unlocked, and then use as much pressure as needed to free the bay.

Figure 20
Figure 20. Removing the hard drive bay

Verify that the hard drive jumper setting is correct, and then use four of the hard drive mounting screws, shown in Figure 21, to secure the hard drive to the bay. The black rubber grommets physically isolate the drive from the bay, reducing noise and vibration. Be sure not to tighten the drive screws more than finger-tight. Overtightening them eliminates the benefit of the rubber grommets.

Figure 21
Figure 21. Securing the hard drive

Connect an ATA cable to the hard drive, making sure that Pin 1 on the cable corresponds to Pin 1 on the drive. Slide the drive bay back into position and move the locking lever to the locked position. Connect one of the peripheral power connectors from the power supply to the hard drive.

The final step in installing the drives is to connect the ATA cables to the motherboard ATA interfaces. Connect the hard drive ATA cable to the primary ATA interface and the optical drive ATA cable to the secondary ATA interface, as shown in Figure 22. (On the ASUS A7N8X-VM/400 motherboard, the primary ATA connector is blue and the secondary ATA connector is black.)

Figure 22
Figure 22. Connecting the ATA cables

Related Reading

PC Hardware Buyer's Guide
Choosing the Perfect Components
By Robert Bruce Thompson, Barbara Fritchman Thompson


The system is now complete except for a few finishing touches. Connect the rear case fan to a power supply connector, and spend a few minutes dressing and tying off all the cables to keep them clear of fans and airflow. Verify all the connections one last time, and make sure you haven't left a tool in the patient. Replace the left-hand side panel, making sure the TAC vent is unobstructed, and connect the monitor, keyboard, and mouse. Finally, connect the power cord, make sure the power supply rocker switch is on, and press the main power switch. The system should come to life and attempt to boot.

As the system comes up, press the Del key to enter BIOS setup. Set the date and time, and configure the other options to your preferences. Make sure the optical drive is set first in the boot sequence, save your changes, and insert your operating system CD in the drive. Restart the system, and install the OS.

We installed Windows XP temporarily to verify that it would install properly, which it did. We then installed Xandros Desktop 3.0 Linux, which is our primary OS. Xandros 3.0 recognized all hardware, including the integrated video, audio, and LAN.

After using the system for several days, we are quite pleased with it, particularly given its low price. Benchmark tests show it to be noticeably slower than our 3+GHz Pentium 4 systems and fast Athlon 64 systems, but it doesn't "feel" much slower in daily use. Although this system wouldn't be our first choice for processor-intensive tasks, it more than suffices for routine web browsing, email, and productivity applications.

The noise level is moderate--louder than we prefer for a quiet working area but not intrusive in a normal office environment, particularly if the system is under a desk. The Antec power supply and case fan contribute little to the noise level; nearly all of it is caused by the small, high-speed CPU cooler fan. Substituting a $20 to $30 quiet CPU cooler such as the Zalman CPNS3100+ or CPNS6000-Cu would allow this system to run almost inaudibly in a normal residential environment.

With the $7.50 Dynatron CPU cooler we used, the Sempron processor idles at 108 degrees Fahrenheit (42 degrees Celsius), a bit warmer than we'd like but still well within specifications. Again, using a better CPU cooler and superior thermal compound would reduce idle operating temperatures significantly, probably to somewhere in the range of 91 to 99 degrees Fahrenheit (33 to 37 degrees Celsius).

Overall, we're delighted with this system. For $500 or so complete ($350 without a monitor, keyboard, or mouse), it makes a perfect second system for a home or dorm room. With some minor targeted upgrades--such as more memory, an inexpensive AGP video adapter for casual gaming, a DVD writer, or a quieter CPU cooler--it may even suit many people as a primary system.

Robert Bruce Thompson is a coauthor of Building the Perfect PC, Astronomy Hacks, and the Illustrated Guide to Astronomical Wonders. Thompson built his first computer in 1976 from discrete chips. Since then, he has bought, built, upgraded, and repaired hundreds of PCs for himself, employers, customers, friends, and clients.

Barbara Fritchman Thompson is a coauthor of "Building the Perfect PC" and "PC Hardware in a Nutshell." She runs her own home-based consulting practice, Research Solutions.

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