AMD ATHLON 64 FX-51 & ASUS SK8N

System Specs

Processor, Motherboard & Drivers Processor AMD Athlon 64 FX-51 Motherboard ASUS SK8N BIOS Manufacturer American Megatrends BIOS Version AMI Bios 2003 ASUS Version 1007 Chipset Driver NVIDIA v3.13 (nForce3 pro-150) Common Components RAM Corsair PC2700 registered DDR SDRAM (2 x 1GB) Video Gainward PowerPack! Ultra/1800 XP Golden Sample (GeForce FX 5950 Ultra) Hard Drive 80GB Western Digital WD800JD 7,200rpm SATA Heatsink Thermalright SLK-948U CPU Fan pcToys 92mm Tornado CD-ROM LiteOn Black 48X/24X/48X/16X DVD/CD-RW Floppy Samsung 1.44MB Power Supply Antec 430W TruePower Case Antec PLUS1080AMG Temperature Monitor MacPower Digital Doc 5
he SK8V pounded through the benchmarks, so we hoped its older sibling could do the same. After all, ASUS has had more time to tweak the SK8Ns once-flaky BIOS. As with the SK8V, we matched the SK8N with the 940-pin Athlon 64 FX-51. ASUS recently released a 939-pin version of the newer FX-53, but we dont expect to see a 939-pin FX-51. Motherboard The SK8N was one of the first AMD Athlon 64 FX-based motherboards to hit the market. Its also one of the only FXbased motherboards that sports NVIDIAs nForce3 pro-150 chipset. The board supports RAID 0, 1, and 0+1, and has a Promise R20378 controller. The SK8N arrived before Gigabit Ethernet became a standard feature, but the board does include a Realtek RTL8201 10/100 LAN controller. Realtek also provided the 6channel ALC650 audio codec. A TI TSB43AB22A chip rounds out the boards most important chips, providing two internal FireWire headers. The board has a 940-pin CPU socket and supports AMD
brackets house two USB 2.0 ports, audio ports (including SPDIF-Out ports, a serial game port, and a FireWire port). We were disappointed to see that the FireWire bracket has only one FireWire portweve seen many brackets that house both FireWire and USB ports. Half-empty brackets just waste space. The motherboard doesnt include Windows-based overclocking software, but it does have several other programs, including InterVideos WinDVD Suite (WinDVD, Win DVD Creator, and WinRip), Trend Micro PC-cillin, and several ASUS BIOS add-ons. The package also includes a printed user guide and a sticker that displays the boards jumpers and front panel connectors. Unlike Athlon XP and 64-based motherboards, 940-pin FX-based motherboards require registered memory. As a result you cant use your old, unregistered memory when you upgrade to the SK8N. When shopping for new memory, keep in mind that most registered memory also includes ECC (error correction code), an unnecessary feature as far as FX-based motherboards are concerned (many
After testing the Athlon 64-based motherboards, which didnt include performance-enhancing dual-channel memory technology, we were glad to see that the SK8N has four dual-channel slots. As a result, you can add up to two pairs of DIMMs to your system. Each pair must have identical DIMMS, but you dont need to use identical pairs. For example, you can use a pair of 256MB, PC3200
AMD Athlon 64 FX-51 (ClawHammer) ASUS SK8N
Stock Performance Overclocked Performance Processor Speed 2.2GHz 2.46GHz FSB 200MHz 224MHz Multiplier Voltage 1.5 1.7 Processor Case Temp Temp 34.2 28.4 39.5 29.5 3Dmark03 PCMark4610 PCMark04 PCMark04 PCMark04 PCMark04 CPU Memory Graphics HDD 5461 4291
Athlon 64 FX and Opteron processors, but we doubt many users will slap an Opteron onto the board. We found a boatload of accessories in the SK8Ns sizeable box. The package includes two SATA cables, a dual-connector SATA PSU adapter, and a bunch of D-brackets. If you dont have many PCI cards, youll love the D-brackets, which add ports but take up PCI slot bays. The
servers use ECC memory). ECC slows system performance, so youll want to disable the feature via the BIOS Memory Configuration section. If youre not sure which memory to buy, take a look at the ASUS Web sites SK8N Overview section (usa.asus.com/products/mb/socket940/sk 8n/overview.htm). The Web page lists dozens of ASUS-qualified DDR333 and DDR400 memory.
DIMMs and a pair of 512MB, PC3200 DIMMS. All told, the four slots support up to 8GB of registered DDR RAM. Unfortunately, ASUS placed the nForce3 pro-150 chipset directly behind the 8X AGP slot. As a result, larger video cards hang over the chipset. You wont have any trouble installing your video card, thanks to the chipsets extremely short aluminum heatsink, but you wont be able to

motherboard by attempting to install a larger heatsink. Our upgrade the American Megaonly other gripe is that ASUS trends 2003 BIOS from placed the power fan header Revision 1001 to 1003. Our right next to the CPU fan SK8N never fully recovered, so header. The headers are identiwe bought a new SK8N for this cal, so make sure youve test (which had Revision 1004) plugged the CPU fan into the and then downloaded the latest correct header before you fire up your system. If you do mix BIOS: Revision 1007. The new them up, we doubt youll toast BIOS took to our motherboard the CPU right away, but we without any trouble, so we werent willing to try. We prepromptly benchmarked the sysfer risks that lead to rewards. tem at default settings. The sysAside from the chipset and tem performed well, scoring fan headers, we like the boards 6150 in 3Dmark03 and 4,147 layout. ASUS placed two of the in PCMark04. boards three IDE connectors Next, we entered the BIOS. ATX 12V PSU FireWire Connector at the front of the board, near The CPU Configuration secConnector the systems optical and hard tion has only two fields: CPU BIOS (American Megatrends) drives. The third IDE connecOverClock in MHz (200MHz SATA Connectors tor stands behind the five PCI to 300MHz) and CPU Chipset (NVIDIA nForce3 pro-150) slots. We were disappointed to Voltage (1.5V to 1.75V). We see that the motherboard has left the VCore at 1.5V and only two SATA connectors. The SK8N raised the frequency. The 1.5V VCore let has a single FireWire header; ASUS added the system coast all the way to 2.4GHz the other FireWire port to the boards I/O (from its default setting of 2.2GHz), at riser. If your chassis has a front panel which point our test PC posted a FireWire port, youll probably want to 3Dmark03 score of 6232 and a ditch the FireWire D-bracket and attach PCMark04 score of 4512. However, the If you have several noisy system fans, the front panel connector to the internal system refused to boot at 2.42GHz until you can enable the ASUS Q-Fan feature, header instead. In fact, youll probably we boosted the VCore to a whopping 1.7 which ratchets down your fan speeds volts, just 0.05V shy of the boards max. need to toss the USB D-bracket too, as the when your system isnt under a full load. We finally maxed out our system at motherboard has only one USB 2.0 headWe like the CrashFree BIOS 2 feature, 2.46GHz with a 1.7V VCore. The test er. The I/O riser eats up the remaining which lets you restore your BIOS from PC scored 6248 in 3Dmark03 and 4610 four USB ports. the driver CD. You can restore a damaged in PCMark04. The system booted at Overclocking BIOS by simply inserting the CD and 2.49GHz and posted a 3Dmark03 score then rebooting the system. As with many other motherboard manof 6265, but it was too unstable to handle When we last matched the SK8N with ufacturers, ASUS adds features to its PCMark04. the FX-51 (see page 91 of PC Modder, BIOS. The SK8N includes several worthFinal Word Spring 2004), we wounded our poor while features, but lacks C.P.R. (CPU Parameter Recall), which appears in the Although we pushed our SK8N-based newer SK8Vs BIOS. C.P.R. resets your system to a slightly higher clock speed than Overclock Comparison system to default settings if your system the SK8V reached, the SK8N couldnt 3Dmark03 freezes, which means you can recover beat either of the other two boards benchfrom most overclocking-related problems mark scores. That said, the SK8N is the ASUS SK8V by simply rebooting. C.P.R. isnt crucial, least expensive board in our pack at $188, Stock Performance 6250 Overclocked Performance 6359 but it lets users avoid clearing the CMOS which means budget overclockers can put via motherboards CMOS jumper. the extra cash towards other components. Gigabyte GA-K8NNXP-940 Luckily, you wont have any trouble And unlike the Gigabyte GA-K8NNXPStock Performance 6204 Overclocked Performance 6300 reaching the CMOS jumper (ASUS also 940, the SK8N didnt have any trouble refers to it as the Real Time Clock RAM running PCMark04. ASUS SK8N jumper), which stands just above the Stock Performance 6150 Overclocked Performance 6248 third IDE connector. by Joshua Gulick

Case Studies

AMD ATHLON 64 FX-51 & ASUS SK8N
MDs Athlon 64 FX-51 isnt just the latest and greatest Athlon XP processor, its the new gaming CPU. The $733 (in 1,000-unit quantities) processor ushers 64-bit computing into the home-user arena. Windows XP 64-bit Edition hasnt taken to the home computing market just yet, but HP has a new workstation that runs 64-bit Windows. Its only a matter of time. The FX-51 doesnt have the XPs blank square on its underbelly, thanks to its 940pin structure. AMD built the core using
The included aluminum heatsink/fan combo has a copper base to dissipate heat. To install it, you simply slide the clips over the frame edges and press a large thumb latch to apply pressure. We didnt even need a screwdriver. AMDs roadmap shows plans to release two FX processors (San Diego and Toledo) in the second half of 2004 and second half of 2005, respectively. AMD will use a new 90nm process on both processors and plans to move the XP to the 90nm process in the second half of 2005.
AMD Athlon 64 FX-51 (Hammer) ASUS SK8N
Stock Performance Overclocked Performance Clock Speed 2.2GHz 2.4GHz Frequency 200MHz 218MHz Multiplier VCore 1.55 1.65 CPU 7081 7720

PCMark2002

Memory 9926 11280

HDD 1344 1253

3DMark 2001 SE 18295 19171
the XPs 0.13-micron SOI (silicon-on-insulator) process, but the FX-51s core has a massive 105.9 million transistors; AMD XPs has 54.3 million. The die is also larger than the XPs Barton at 193mm. To counter the extra heat, AMD built a heat spreader onto the processor. The FX-51 uses HyperTransport and a single data link (the Opteron uses three) that operates at 1,600MHz and has a 6.4GBps maximum bandwidth. The FX51 has a 2.2GHz clock speed, 128KB L1 cache, an extra-large 1,024KB L2 cache, and handles SSE2. It also has a 128-bit memory controller and requires registered DDR memory (supporting up to PC3200). You can buy ECC registered DIMMS or non-ECC registered DIMMs; the CPU doesnt require ECC. (The Athlon 64 isnt as fast as the FX-51, but it doesnt require registered memory.) The CPU uses a new pressure clip and socket frame and includes a backplate that attaches to the mobos back. A sturdy frame attaches to the mobos two mounting holes.
Specifications We bought an Antec PLUS1080AMG Performance Plus to house our test rig. The case had three fans (two in back, one on the side panel) and a 430W TruPower PSU. Our system had a Seagate ST380013AS Barracuda SATA 7200rpm hard drive, a 1GB kit (two 512MB modules) of Kingston KHX3200AK/1G DDR 400 PC3200 memory, and a Lite-On LTC48161H 48X/24X/48X/16X CD-RW/ DVD-ROM. We chose an NVIDIA GeForce FX 5900 Ultra-based Leadtek WinFast A350 Ultra TDH (My Vivo Edition) with 256MB RAM and downloaded the latest NVIDIA drivers (version 45.23). We loaded WinXP Pro so we could use the same 32-bit benchmarks weve used to evaluate the other AMD processors. Motherboard XP-based boards wont accommodate the FX-51, so youll need a new mobo. We chose the ASUS SK8N, one of the first boards to support these CPUs.
Rather than a traditional northbridgesouthbridge layout, the SK8N uses a single NVIDIA nForce3 Pro 150 chip, which sits directly behind the AGP 8X port and thus, under your AGP card. The chip also has a short heatsink that further reduces the gap between card and chip. The mobo does have two holes near the chip, and the heatsink is removable, so you may be able to attach various (short) cooling devices. The SK8Ns four DIMM slots stand parallel to the top of the board, just above the CPU, which means you wont have to fight with your AGP card to insert memory. The DIMM slots stand in two sets of two because the board has dual-channel technology. The SK8N supports up to 8GB of PC1600-PC3200 memory. Note that the board requires registered memory, but dont pay more for non-ECC registered RAM; the BIOS lets you disable ECC. The 940-pin CPU socket sits below the 3DMark2001 SE Increase DIMM slots, well away from capacitors, risers, or other components 876 that usually clog up the socket area. ASUS attaches its own CPU backplate and frame, making the installation that much easier. ASUS put a single ATA 133 and two ATA 133/100 connectors on the SK8N. Two connectors sit under the PSU connector on the boards right side, while the other stands below the nForce3 Pro 150. If you use that connector, youll probably need to run the cable over your AGP card. You can avoid blocking airflow if you use tuckable, twistable SATA cables. The two SATA connectors and a Promise R20378 RAID controller stand behind the motherboards five PCI slots. The board supports RAID 0, 1, and 0+1. The SK8Ns CNR includes two PS/2, parallel, serial, four USB 2.0, Ethernet, FireWire, and three audio ports. Inside is a FireWire connector and a connector that supports 2.0 USB ports. Extras include the overclocker-friendly ASUS CrashFree BIOS 2, it replaces your systems damaged BIOS, and ASUS QFAN, which monitors your system and controls fan speed when switching between heavy and light loads. The SK8N also

ATX 12V Connector

Audio Codec BIOS (American Megatrends)
I/O Controller FireWire Controller
SATA Controller Standby Power LED SATA Connectors

940-pin CPU socket

NVIDIA nForce3 Pro 150
includes Trend Micro PC-cillin 2002 and ASUS EZ Flash, MyLogo2, and PC Probe. Overclocking The SK8N was one of the first mobos to support the FX-51, so we werent surprised it gave us some trouble. We inserted the Windows CD, powered on the system, and pressed F6 to open a Windows Setup screen that asked us to specify a hard drive. We selected Specify Additional Device, inserted a floppy that contained the SATA drivers, and selected WinXP Promise FastTrak 376/378 Controller. We expected Windows to perform the installation, but it couldnt find our hard drive. We pressed F3 to restart the system and entered the RAID utility by pressing CTRL-F. RAID 0, a striped configuration, supports a single hard drive, so we selected RAID 0 and restarted. Windows installed without trouble, so we benchmarked our system at its default settings: an 11X multiplier, 200MHz frequency (400MHz FSB;
2.2GHz clock speed), and 1.55V VCore voltage. The system scored well in both benchmarks, posting 7067 (CPU), 9954 (Memory), and 1275 (HDD). ASUS doesnt offer Windows-based overclocking software, so we entered the American MegaTrends 2.54 (ASUS Revision 1001) BIOS, scrolling to the Advanced tab. The mobo disables ECC by default. Enable it (if you have ECC memory) by selecting Chipset, NorthBridge
Configuration, ECC Configuration, and changing the Master ECC Enable field to Enable. We overclocked in non-ECC and ECC modes. The ECC mode lowered the 3DMark2001 score about 160 3DMarks. The CPU Configuration menu houses the CPU OverClock In Mhz field (which lets you adjust the frequency from 200MHz to 300MHz) and the CPU Voltage field (which supports VCore voltages from 1.55V to 1.75V). We like the frequency range but wish ASUS bumped up the max voltage, as the XP 3200+ performed best after raising the VCore voltage to 1.85V. Revision 1001 doesnt let you adjust the CPUs multiplier. The latest BIOS (Revision 1003) adds this feature, which means you have to intall the new BIOS to change the multiplier. Before doing this, we used Revision 1001s features. The system remained stable at 1.55V until it hit 213MHz but couldnt complete 3DMark2001. At 1.65V and 218MHz (436MHz FSB; 2.4GHz), the system posted 19171 in 3DMark2001, an 876-point increase. We couldnt push the system past 218MHz, so we downloaded Revision 1003, installed the BIOS and rebooted. The system posted, started to load Windows, and then crashed. We did load Windows once, but the system eventually crashed. Despite reinstalling the original BIOS, we werent able to load Windows or reinstall the OS before we went to press. We suspect we damaged the mobo while installing the new BIOS. Final Word We cant wait to see FX-51 power more 64-bit apps. Manufacturers are quickly producing boards to support AMDs new gamer/power-user processor family, so expect new boards to work out the kinks. If you prefer VIA chipsets, take a look at ASUS SK8V, which feature the VIA K8T800 northbridge.

by Joshua Gulick

Overclock Comparison 3DMark2001 SE
5 AMD Athlon 64 FX-51 Stock Performance Overclocked Performance AMD Athlon XP 3200+ Stock Performance Overclocked Performance AMD Athlon XP 3000+ Stock Performance Overclocked Performance 18295 19171

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