iXBT Labs - Computer Hardware in Detail






ASUS A8N32-SLI Deluxe — a Motherboard on the Top Gaming Chipset (NVIDIA nForce4 SLI X16)

February 27, 2006

  • NVIDIA nForce4 SLI X16 chipset (nForce SPP 100 northbridge and nForce4 SLI southbridge)

At the press conference devoted to new chipsets from NVIDIA (integrated GeForce 6100/6150 and discrete nForce4 SLI X16), Drew Henry, general manager of platform business at NVIDIA spoke about the present and the future of SLI platforms with flatness, unusual to managers of that rank. He said that they manufactured the chipset for both platforms — AMD as well as Intel — though they couldn't make Intel processors more attractive to gamers. Of course, this statement flattered AMD representatives to some degree. But market facts are no less categorical: There have been much more nForce4 SLI -based motherboards sold for the AMD platform than for Intel. We do not deny the significant difference in performance, but this phenomenon with respect to mainstream is due to much earlier launch of the AMD version. What concerns the nForce4 SLI X16 chipset, being radical about it is probably appropriate. Enthusiasts, who worry about maximum performance in games to such degree that they are ready to spend a lot of money to avoid even such a rare bottleneck as x8+x8 SLI mode, just cannot be unaware of processor preferences of modern games. Fortunately they are quite distinct.

As a result, NVIDIA decided to minimize its efforts and use the old nForce4 SLI (IE) as a northbridge for the Intel platform, especially as it did not contain excessive functionality for the two-chip solution, and design a new product for AMD — nForce SPP 100. Both solutions use a chip from the single-chip nForce4 SLI core logic as a southbridge. Bridges are connected with HyperTransport bus, providing a total of 40 PCI Express lanes. In its turn, ASUS also decided not to complicate matters and updated its range of products, by launching similar in functionality and concept A8N32-SLI Deluxe and P5N32-SLI Deluxe motherboards with Socket 939 and Socket 775 correspondingly, which are based on nForce4 SLI X16. External controllers on these motherboards match to within chip models! Differences come down to power supply units, cooling systems, and of course PCB layout.

The new northbridge nForce SPP 100 for the AMD modification of the chipset is made from GeForce 6150 by removing integrated video. So it's also manufactured by 90-nm process technology and, unlike nForce4/SLI, it does not contain peripheral bus controllers and other functionality, implemented in southbridge. Such a solution is more logical and cheaper than just merging two sterling chips from the previous line. It means that we can hope for a significant price drops for motherboards on nForce4 SLI X16, after the initial demand is filled. Interestingly, imagination of engineers is not limited to using this chipset in motherboards with two full-speed PCI Express x16 ports — later on we shall review an alternative design from ECS.

Fitting to a Deluxe model, ASUS A8N32-SLI Deluxe functionality is exhaustive. We can complain only about having to install some ports on the front panel, as the rear panel cannot accommodate all connectors. Memory slots are divided by channels in a relatively rare way: to enable dual channel mode, two memory modules should be installed into next but one slots, not into neighboring slots (it's good for ventilation they say). If you by any chance install both memory modules into the slots of the same channel, the motherboard will no start up — this mode is not supported, which is noted in the documentation.

The motherboard has a good layout, we'd like to note a proprietary ASUS solution — sidelong IDE connector. The only problem is with the Clear CMOS jumper, it "conflicts" with a latch on the second PCI Express x16 slot and will most likely be blocked by a bulky cooler of the second video card. We also have gripes with the arrangement of PCI slots: the first PCIEx16 slot had to be moved from the processor socket due to the specific chipset cooling system; so if you install two "two-slot-thick" accelerators, there will be only one PCI slot available. Green LED indicates power on the motherboard. You are not recommended to install or remove any system components, when this LED is on.

The motherboard uses a fanless cooling system with heat pipes. But unlike ASUS P5N32-SLI Deluxe, both bridges of the chipset are united into one circuit, which can be cooled by only one optional fan. It should be noted that during our tests with top processors (Athlon 64 4000+ and the overclocked to 2.8 GHz dual core model) in an open testbed the motherboard was stable without using additional fans. It turned out that the voltage regulator didn't even need passive cooling. It should be emphasized: the above said does not at all mean that you can take it as an instruction, moreover to install this motherboard into a tight PC case without additional fans and overclock it to maximum. Unlike processors, chipsets do not have an "automatic cut-out" procedure to avoid overheating (this feature is rarely implemented in motherboards or their BIOS). Constant operation in bad temperature conditions may reduce the service life of a chipset and a motherboard. They may even break down before they are outdated. Of course, additional cooling must be organized smartly — in particular, ASUS recommends to install an additional bundled fan on the heatsink of the on-board cooling system only in case of passive or water cooling of the processor. Otherwise, CPU fan will suffice.

A separate mention should be made of an eight-phase(!) switching voltage regulator of a processor: judging from the crying label on the box and advertisements in the product descriptions, this innovation is a pride of ASUS engineers. So, the CPU power circuit contains one field-effect transistor per channel, three 1000 uF capacitors, and six 820 uF capacitors. The board is also equipped with a voltage regulator for memory and expansion cards (including five 820 uF capacitors and two 1800 uF one, reinforced with L elements). The motherboard incorporates capacitors from respected Sanyo and United Chemi-Con. What's the point in using so many phases in a voltage regulator? Contrary to the prevailing opinion, it's not a reserve for the future or satisfying requirements of overclocked processors in increased capacity of a "power station" of the motherboard (all these are just consequences). You may notice that in this case we have the same (typical) total number of field-effect transistors, but only one transistor is used per phase instead of usual 2-3 transistors. As you know, a switching voltage regulator reduces a signal to the required level by applying impulses of maximum amplitude to the power circuit, which alternate with a complete lack of signal. Multiple capacitors and L elements are used to shape the output signal as a smooth sinusoid rather than saw-tooth. But increasing the number of impulses (generated by the regulator per unit of time) can actively influence the quality of the output signal. The more frequent the impulses, the smaller amplitude will obviously be required for each impulse.

The results: all other things being equal, we have a flatter output signal, which can be smoothed over by lower capacitance; overall efficiency of the regulator grows (by 10% when we switch from 4 to 8 phases, CPU power consumption being within 70 (and more) Watts); hence the reduced heat release. What concerns the potential situation to power up voracious chips, there is no direct relationship to the number of voltage regulator phases (it makes sense to count a total number of transistors). According to ASUS, the efficiency drops linearly starting from 110 Watts. But maximum voltage stability is very important for overclocking. Irregardless of power consumption of your overclocked processor, you can raise the voltage to a higher level than in case of unstable voltage, when you have to take into account a safety margin for surges, which can easily freeze your system. Nevertheless, despite all advantages, we don't expect mass upgrade to voltage regulators with 6 or more phases so far, as saving on capacitors does not compensate for the increased overall cost.

There are no empty seats on the motherboard, except for several capacitors, which should have been there according to the design, but turned out "excessive" in the power circuit. ASUS manufactures two modifications of the A8N32-SLI model: simple Deluxe and Deluxe/WiFi with a miniature WiFi-g adapter with a USB interface near the rear panel; so it occupies one of USB ports and places another on the rear panel. Note that there is no regular (non-Deluxe) modification of this motherboard (chipset oblige!). A8N32-SLI design differs much from models on the nForce4/SLI chipset, as this chipset has two bridges instead of only one. Motherboard dimensions — standard ATX (305×245 mm), nine-screw mount, all corners are firmly fixed.

ASUS engineers paid a lot of attention to the quality of the power supply unit and a cooling system. We have never seen an 8-phase switching voltage regulator before — it's an excellent solution, yet expensive. The chipset cooling system with heat pipes as well as heatsinks on field-effect transistors allow to do fine without an extra fan in most cases. The PCB layout has almost no drawbacks. It's convenient to assemble the system even though the model has rich functionality. So we unhesitatingly award the ASUS A8N32-SLI Deluxe motherboard for its original design.

System monitoring (ITE IT8712F-A, according to BIOS Setup)

  • CPU voltage, +3.3, +5, and +12 V
  • RPM of 3 fans
  • CPU and board temperatures (by the corresponding embedded sensors)
  • Q-Fan Control — automatic control of the fan rotational speed depending on temperatures of monitored components. The BIOS version that we used for our tests does not allow to configure the control method. CPU temperature threshold is rather low by default (45-50°C), when it's exceeded, the CPU fan speeds up (not gradually, but abruptly) and retains maximum rpm until the temperature goes down below the threshold. The fan rotates at minimum rpm at lower temperatures, dead stop of the fan is not allowed so far. However, this functionality will certainly be enhanced in the next BIOS versions. The current version is still buggy (read below). What concerns smart cooling control, ASUS motherboards are traditionally good at it.

Onboard ports, sockets, and connectors

  • Processor socket (Socket 939, official support for all AMD Athlon 64/X2/FX processors, Sempron is not forgotten either, even in the printed manual)
  • 4 x DDR SDRAM DIMM (up to 4 GB DDR200/266/333/400, dual channel operating mode is supported)
  • 2 x PCIEx16 for video accelerators (both of them always work in x16 mode)
  • 1 x PCIEx4 (support for x1 expansion cards)
  • 3 x PCI
  • Power connectors: standard ATX 2.2 (24 pins), 4-pin ATX12V to power up a processor, and 4-pin peripheral connector for video cards (you are recommended to use it in case of a 20-pin ATX connector in a PSU or if a video card does not have its own power supply)
  • 1 x FDD
  • 2 x IDE (Parallel ATA) for 4 ATA133 devices — chipset-based
  • 5 x SATA-II (Serial ATA II) for 5 SATA300 devices: 4 of them are chipset-based, connected drives can form RAID 0, 1, 0+1, 5, and JBOD; the other one is supported by an additional controller, this drive can be added to RAID 0 or 1 with a hard disk drive connected to the external SATA port on the rear panel
  • 3 connectors for brackets with 6 additional USB ports
  • 2 connectors for brackets with 2 FireWire ports
  • COM-port connector
  • GAME/MIDI port connector
  • 1 x CD/DVD audio connector
  • AUX-In connector
  • Connectors for analog audio ins and outs on the front panel
  • Connector for a chassis intrusion sensor
  • 6 fan headers with rpm control (two of them support smart rpm control depending on temperatures of cooled components).

Back panel (left to right, blockwise)

Click the image to open the rear view of this motherboard
  • PS/2 mouse and keyboard
  • 1 x coaxial and 1 x optical (Toslink) S/PDIF-Out, 1 x LPT, 1 x external Serial ATA II (for e-SATA devices with their own power supplies)
  • 6 x Analog Audio (Center/Sub, Side-Out, Rear-Out, Line-In, Front-Out, Mic-In)
  • 2 x USB and 1 x RJ-45 (Gigabit Ethernet)
  • 2 x USB and 1 x RJ-45 (Gigabit Ethernet)

Package Contents

  • Package: AI Life series box of the standard dimensions in a jacket with a flip cover listing motherboard's features
  • Documentation: User's Manual in English and an insert with detailed description of the functionality
  • 5 x Serial ATA with 3 power converters for 5 devices
  • 1 x ATA66, 1 x ATA33 (for CD-ROM), 1 x FDD (all of them bear ASUS logo)
  • Rear panel bracket with a COM port
  • A rear panel bracket with a GAME port and two USB ports
  • A rear panel bracket with two FireWire ports (6-pin and 4-pin)
  • SLI Bridge (cable)
  • Optional fan to be installed on the chipset and voltage regulator heatsink
  • Rear I/O shield
  • CD with drivers and proprietary ASUS utilities
  • CD with InterVideo WinDVD Suite (programs for creating DVD with video, photos, etc. It includes PhotoAlbum 1.0, WinDVD Creator 2, DVD Copy 2.5, Disc Master 2.5).

The set of proprietary utilities includes: MyLogo2 (display a custom logo at system startup), Update (flash BIOS under Windows, allows to search and download the latest version from the official web site), PC Probe II and AI Booster (system monitoring and overclocking under Windows).

Integrated Controllers

  • Audio, based on AC'97 Realtek ALC850 Audio Codec supporting 7.1 surround sound audio, with front line-in/out and two S/PDIF-Out jacks
  • 2 x Gigabit Ethernet supporting 10/100/1000 Mbit/s: one of them is based on the chipset (supporting the hardware firewall) and Marvell 88E1111-RCJ PHY controller, the second is based on a separate Marvell 88E8053 chip (connected to PCI-E bus)
  • SATA-II RAID controller, based on Silicon Image SiI3132CNU chip supporting two SATA300 devices (including one external device) and RAID levels 0 and 1
  • FireWire, based on the Texas Instruments TSB43AB22A chip, supporting 2 x FireWire.

The integrated audio quality was tested in 16bit, 44 kHz using the RightMark Audio Analyzer 5.5 test application and the Terratec DMX 6fire sound card:

Frequency response (from 40 Hz to 15 kHz), dB:
+0,08, -0,75
Noise level, dB (A):
Dynamic range, dB (A):
THD, %:
Intermodulation distortion + Noise, %:
Channel crosstalk, dB:
IMD at 10 kHz, %:

General performance: Good (Details). There is nothing much to say about the quality of the analog audio output in this motherboard: all parameters are on the standard (for AC’97) good level.

Proprietary technologies and peculiarities

  • Fanless Design — a common cooling system for the chipset and the voltage regulator; it uses heat pipes to get rid of fans on the motherboard operating in the standard mode
  • Q-Fan 2 — automatic rpm control of the CPU fan and the fan plugged to the Chassis Fan connector depending on the CPU and system temperatures correspondingly
  • Stack Cool 2 — an additional (from the back side) metallized layer of the PCB, which allows to channel the heat away from the main chips
  • PEG Link Mode — automatic overclocking of PCI-Express bus depending on video card's requirements to the additional bandwidth (4 modes are available)
  • AI NOS (Non-Delay Overclocking System) — dynamic overclocking of a processor depending on its load. The clock grows only under maximum CPU load, the rest of the time it operates at its standard clock (or at the clock, reduced by the Cool’n’Quiet driver)
  • AI Net 2 — both network controllers automatically detect a damaged cable - LAN Cable Status option in BIOS and a proper Windows utility
  • C.P.R. (CPU Parameter Recall) — when the system hangs due to overclocking failure, it automatically rolls back to default BIOS settings
  • CrashFree BIOS 2 - automatic BIOS restoration from a floppy or a bundled CD after a failed flashing attempt


Jumpers and switches Clear CMOS jumper  
In BIOS v2.58 from AMI Allows to disable specific CPU functions + K8 Cool’n’Quiet
Memory timings + 1T/2T Memory Timing, CAS Latency, Min RAS Active Time, Row Precharge Time, RAS to CAS Delay, Row to Row Delay, Row Cycle Time, Row Refresh Cycle, Read-To-Write Time, MCT Extra Timing Mode (TREF, TWCL, R/W Queue Bypass Count, ByPass Max, Idle Cycle Limit, Dynamic Idle Cycle Center, DDR Driving Strength, Enable 32-Byte Granularity, Twr, DDR Input Strobe Skew), DDR Clock Skew
Memory frequency selection + Auto, standard frequencies within 100—250 MHz (you actually specify a multiplier to the HTT frequency)
HT bus setup + frequency for both buses (Auto, 200, 400, 600, 800, 1000, 1200, 1400, 1600 MHz) and capacity (8 or 16 bit for the processor-northbridge bus and 4, 8, or 16 bit for the northbridge-southbridge bus) fine-control of the northbridge-southbridge bus frequency (200—300 MHz at 1 MHz steps)
Peripheral bus frequency control + PCI-E = 100—200 MHz at 1 MHz steps
PCI IRQ manual assignment -  
FSB frequency setup + 200—400 MHz at 1 MHz steps
CPU multiplier + from x6 at 0.5 steps
CPU core voltage control + 1.4250—1.5625 V at 0.0125 V steps and a separate increase by 0.2 V
Memory voltage control + Auto, 2.60—3.20 V at 0.05 V steps
Chipset voltage control + 0.1 V increase (up to 1.6 V for the southbridge and up to 1.3 V for the northbridge)
HT bus voltage control + 0.1 V increase (up to 1.3 V) for the bus from CPU to Northbridge

We used BIOS 0703 dated 04.11.05, the latest available BIOS version at the time of our tests. The mentioned BIOS parameters are available in this version, but the viability of non-standard settings hasn't been tested. In the latest beta version available to public (0805 dated 09.11.05) there appeared support for new, not yet officially released processors, as well as a modified HT frequency control method: instead of specifying the value in MHz, we now have multipliers (x1—x8), which agrees well with fine-control of the HT frequency. By the time we published this article, there appeared two more official versions (the current version is 1009 dated 21.12.05). They allow to raise FSB frequency to 500 MHz, have individual control of each SATA port, various bugs are fixed, etc.

A separate mention should be made of rare settings for caching modes and Scrub parameters for ECC memory. BIOS contains the LAN Cable Status option to detect damaged network cables. BIOS is not yet fine-tuned - there is the empty ARM Configuration section, which should contain a set of standard parameters (according to the documentation).


Testbed configurations:

  • CPU: AMD Athlon 64 4000+
  • Memory: 2 x 512 MB Corsair XMS3200 TwinX (DDR400, 2-2-2-5)
  • Discrete video: ATI Radeon X800 XT, 256 MB DDR
  • HDD: Seagate Barracuda 7200.7 (SATA, 7200 rpm)
  • Power supply unit: Chieftec GPS-400AA
  • OS: Windows XP SP2

We've taken for comparison a recently reviewed (one of top solutions) ASUS model on the nForce4 SLI chipset — ASUS A8N-SLI Premium.

Test ASUS A8N-SLI Premium (NVIDIA nForce4 SLI) ASUS A8N32-SLI Deluxe (NVIDIA nForce4 SLI X16)
Archiving with 7-Zip, min:sec 7:28 7:32
MPEG4 (XviD) encoding, min:sec 5:06 5:06
Unreal Tournament 2004 (Low@640x480), fps 67.1 67.6
Unreal Tournament 2004 (Highest@1600x1200), fps 57.4 61.5
FarCry (Low@640x480), fps 180 184
FarCry (Highest@1600x1200), fps 78 80

The results confirm the assumption that the new motherboard works with memory on a par with its direct predecessor (and all other motherboards for AMD K8 processors of the same socket). The effect of two video cards working in full-speed mode (x16+x16) should be reviewed separately. However, we should make a little comment on the efficiency of the new northbridge (nForce SPP 100) in case of a single video card. Our constant users may remember that nForce4 Ultra/SLI-based motherboards demonstrated a tad lower performance in most graphics modes we use for testing games, but in some cases the situation was contrary. Then we assumed that the trouble was in the SLI unit (nForce4 Ultra also has this unit, though it's not explicitly activated). This unit has been obviously overhauled in the nForce SPP 100 (to work in full-speed mode). It will be logical to assume that the effect is evident. Now, nForce4 SLI X16 -based motherboards must be on a par with motherboards on chipsets from other manufacturers in case of a single video card.

Bottom line

This model definitely deserves the title of the best gaming motherboard from ASUS. It can be recommended as a basis for an ultimatistic gaming station. But what concerns a wider usage, the A8N32-SLI Deluxe does not seem to have any prospects (as well as any other models on nForce4 SLI X16), at least as long as customers have to pay for the x16+x16 mode. Fanless cooling of the chipset and the voltage regulator is a very interesting feature, but it does not make this model unique. The overall functionality level of this model corresponds to other top solutions on the market.

This model on the manufacturer's web site (Russian mirror)

The motherboard is kindly provided by the manufacturer

Dmitry Vladimirovich (lpt@ixbt.com)
February 26, 2006

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