A high-performance system should have 1GB or 2GB of memory. At the time we built this system, the DDR2 memory used by the Intel D925XCV motherboard was still expensive and hard to come by, so we decided to install two 512MB modules for a total of 1GB. That leaves two free memory slots, so we can later expand total memory to 2GB or 3GB. This was the first system we'd built with DDR2 memory, so we had no experience by which to judge. Based on more than a decade of good experience with other types of Crucial memory modules, we elected to install a pair of Crucial 512MB Intel-validated CT16HTF6464AG-53EB2 PC2-4200U modules.
The ASUS SK8N motherboard requires registered DDR-SDRAM DIMMs, which are both more expensive and slower than standard unbuffered DDR-SDRAM DIMMs. If we used the SK8N, we'd install two Crucial CT6472Y40B 512MB PC3200 CL3 Registered DIMMs for total system memory of 1GB, or four of those modules for a total of 2GB. Alternatively, if we wanted to have 2GB initially but leave slots open for future memory expansion, we'd install two Crucial CT12872Y40B 1GB PC3200 CL3 Registered DIMMs.
Video Adapter: nVIDIA GeFORCE 6800 GT PCI Express
Although Xandros Linux is our primary desktop OS, this system will dual-boot Windows for gaming. Accordingly, we needed a PCI Express video adapter that provided excellent 3-D gaming performance under Windows and was also well supported by Linux.
We gulped when we checked the prices of the fastest ATi and nVIDIA PCI Express graphics adapters. We're building an ultimate system, but it still seemed ridiculous to use a $650 video adapter. Fortunately, excellent high-performance video adapters are available for much less. Although we were tempted to use a midrange adapter such as a ATi RADEON X700-series adapter or the nVIDIA 6600, new-generation games such as Doom 3 demand everything a video adapter can give, and then some. In the $350 to $400 price range we decided was reasonable, the choice came down to the nVIDIA GeForce 6800 GT versus the ATi RADEON X800 Pro.
Both are superb video adapters, with excellent image quality and 3-D performance only slightly behind the fastest current-generation adapters. For example, while only a few months ago the ATi RADEON 9800XT sold for $500 and up and was the fastest mainstream video adapter available, the current sub-$400 X800 Pro and 6800 GT adapters are both nearly twice as fast. Choosing between the ATi X800 Pro and the nVIDIA 6800 GT was difficult.
nVIDIA adapters have a huge performance advantage for OpenGL games like Doom 3. In fact, a $400 nVIDIA GeForce 6800 GT adapter outperforms a $650 ATi X800 XT Platinum in most Doom 3 benchmarks. Conversely, ATi has the edge for most DirectX games.
Either one would be a good choice, but we eventually decided on the nVIDIA 6800 GT based on its higher performance for the games we play and the better reputation of nVIDIA Linux drivers. If you run Windows and play mostly DirectX games, the ATi X800 Pro may be the better choice. Regardless, these two adapters are more similar than different in both performance and video quality. You'll be happy with either.
Audio Adapter: Embedded
The Intel D925XCV motherboard includes the excellent embedded Intel High Definition Audio 7.1 audio subsystem, which more than suffices for most people's needs. Although Intel officially supports only Red Hat Enterprise Linux 3, SuSE Linux 9.0/9.1, and Red Flag Linux 4.0/4.1, the Intel HD Audio Linux drivers should work properly with any current Linux distribution. If you build an Athlon 64 system on an nForce3-series motherboard, you'll find that the embedded audio is excellent and well-supported by Linux.
If you need even more audio features and better sound quality than embedded audio provides, choose the M-Audio Revolution 7.1 audio adapter. Based on the superb Envy 24HT chipset, the Revolution 7.1 provides top-notch audio quality, 7.1 speaker outputs, and a coax SP/DIF connector. The Revolution 7.1 is good enough for anyone except those who work with audio professionally. M-Audio doesn't provide Linux drivers directly, but the Revolution is well supported by the free ALSA and commercial OSS drivers.
One of the new features of the 925X chipset is support for NCQ (Native Command Queuing). NCQ allows a hard drive to queue incoming requests and execute them in the most efficient order, regardless of the sequence in which they are received.
NCQ uses the same algorithm as an elevator. For example, an up-bound elevator stops in sequence at each floor for which a button has been pressed, regardless of the order in which the buttons were pressed. In the same way, an NCQ drive queues requests and acts upon them according to the current position of its heads and their direction of travel, rather than fulfilling requests in the order in which they are received. In contrast, a standard hard drive fulfills requests in the order they are received, which is analogous to an elevator that is programmed to respond to button presses in the order they are received rather than stopping on intermediate floors.
NCQ provides two major benefits. First, because NCQ uses a more efficient scheduling algorithm, an NCQ drive is considerably faster than a standard drive. In our tests, the 7,200-rpm Seagate Barracuda NCQ hard drive matched and often exceeded the performance of a non-NCQ 10,000-rpm Western Digital drive. Second, the more efficient scheduling of the NCQ drive minimizes head movements, which contributes to greater reliability and longer life. SCSI hard drives have long used NCQ, which is one of the major reasons for their better reliability and higher performance under load relative to standard ATA drives.
Implementing NCQ requires both an NCQ-compliant ATA interface and an NCQ-compliant hard drive. The Intel D925XCV motherboard provides NCQ-compliant Serial ATA interfaces. We decided to install two hard drives in this system because we intend to use RAID 1 mirroring. For NCQ-compliant drives, we chose the 160GB Seagate ST3160827AS Barracuda 7200.7 SATA.
Figure 2. Seagate Barracuda 7200.8 hard drive (image courtesy of Seagate Technology)
Note: Although we used Barracuda 7200.7 drives in our project system, you'll probably want to use Barracuda 7200.8 drives. Our sources at Seagate tell us that Barracuda 7200.8 drives will soon be shipping in volume, with capacities of 250GB, 300GB, and 400GB, in PATA and SATA NCQ models, with 8MB or 16MB of cache. As is true of earlier Barracuda models, the Barracuda 7200.8 drives are cool running and very quiet, producing as little as 20 dB at idle.
We've used and recommended Seagate Barracuda ATA hard drives for seven drive generations now, and our opinion hasn't changed. Barracuda drives are fast, cool-running, very quiet, and extremely reliable. We'd choose the same drives for an Athlon 64 system, although existing Athlon motherboards do not support the NCQ functions of the drive.