iXBT Labs - Computer Hardware in Detail






ASRock 939S56-M — a Motherboard Based on SiS756

  • SiS756 chipset (SiS756 Northbridge and SiS965L Southbridge)

We haven't reviewed ASRock motherboards for a long time. And today we have an opportunity to test another budget model from this manufacturer. ASRock 939S56-M is equipped with a chipset from SiS (SiS756), this fact means that the product price should be low. It should be noted right away that unlike the previously reviewed ASRock K8 Combo-Z and ASRock K8Upgrade-760GX, this motherboard does not feature any original technologies and designs, it's just a work horse for a mass consumer. We have an impression that the designers intended to create a solution as cheap as possible but still modern. Socket 939 combined with PCI Express must arouse interest of common home users. At the same time, 939S56-M peripheral capacities are minimal: it uses the most unassuming (among modern SiS solutions) Southbridge and is limited by its features. Additional controllers include cheap PHY controllers from Realtek for the network and audio controllers of the southbridge, but the audio codec supports 8 channels instead of 6 ones. The number of expansion slots and peripheral connectors does not boggle imagination either: two PCI slots, one PCIEx1 and just two SATA slots are insufficient for these times. However, there are four memory slots instead of only two, which is important for many users.

As appears from the above, the PCB layout is rather convenient, despite the miniature microATX board dimensions. Regular full-sized models have an FDD connector near the bottom (it's left on the photo) edge, which may hamper the connection in high towers, but in this case the cable is certainly long enough. However, there are still some drawbacks: we would note a relatively high Northbridge heatsink, which is so close to the processor socket that it interferes with the cooler installation; it may even make it impossible to install a cooler with an expanding heatsink. We can also note the location of both power connectors on a motherboard near the rear panel, so that their cables will overhang the processor cooler. Access to one of the jumpers is hampered when a motherboard is installed into a PC case. There are no jumper descriptions on the PCB, but there are tips for users instead :)

The 3-phase switching voltage regulator of the processor incorporates six 3300 uF capacitors and four 1200 uF ones. The board also contains a voltage regulator for memory consisting of six 1000 uF capacitors. In general, critical circuits incorporate electrolytic capacitors from OST (we are not very enthusiastic about it) and United Chemi-Con. There are no empty seats on the motherboard, which is only natural considering that the 939S56-M is the only ASRock model for Socket 939 based on the SiS756 chipset. Motherboard dimensions — 244x224 mm (slightly smaller than the standard microATX, six-screw mount, one edge sags a little).

System monitoring (Winbond W83697HF, according to BIOS Setup)

  • CPU voltage, +3.3, +5, +12 V
  • RPM of 2 fans
  • CPU and board temperatures (by the corresponding embedded sensors)

Onboard ports, sockets, and connectors

  • CPU socket (Socket 939, claims to support all existing AMD Sempron/Athlon 64/FX/X2 processors)
  • 4 x DDR SDRAM DIMM (up to 4GB DDR266/333/400; supporting dual-channel mode when both channel slots are filled symmetrically)
  • PCIEx16 slot for video accelerators (there may be problems with cards based on ATI Radeon X300/SE, the list of approved models is published on the official web site)
  • PCIEx1 slot
  • 2 x PCI
  • Power connectors: standard ATX 2.1 (20 pins) and 4-pin ATX12V for a processor
  • 1 x FDD
  • 2 x IDE (Parallel ATA) — both are chipset-based, supporting up to four ATA133 devices
  • 2 x SATA150 (Serial ATA) — both are chipset-based, connected drives can form RAID 0 and 1
  • 2 connectors for brackets with 4 additional USB ports
  • 1 x CD/DVD audio connector
  • Connectors for analog audio ins and outs on the front panel
  • Connector for a Game port on a bracket
  • 1 x standard IrDA connector
  • 2 x fan headers (both offer rpm control).

Back panel (left to right, blockwise)

Click the image to open the rear view of this motherboard
  • PS/2 mouse and keyboard jacks, 1 x LPT and 1 x COM
  • 2 x USB
  • 2 x USB and 1 x RJ-45 (Fast Ethernet)
  • 6 x analog audio jacks (Line-In, Front, Mic-In, Rear, Center/Sub, Side)

Package Contents

  • Package: a small box of the standard ASRock design
  • Documentation: brief motherboard guide in seven languages, a poster with brief SATA HDD installation instructions
  • Cables: 1 x SATA (with a power converter), 1 x ATA 66/100/133 and 1 x FDD cable
  • Rear I/O shield
  • CD with drivers and utilities as well as with PC-cillin 2004 (unassuming antivirus).

Integrated Controllers

  • AC'97 Realtek ALC850 7.1-channel audio codec with front line-in/out jacks
  • Network, supporting 10/100 Mbit/s, based on the chipset and Realtek RTL8201CL (PHY).

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:
+0,07, -0,61
Noise level, dB (A):
Dynamic range, dB (A):
THD, %:
Intermodulation distortion + Noise, %:
Channel crosstalk, dB:
Very good
IMD at 10 kHz, %:

General performance: Good (Details).

Proprietary technologies and peculiarities

  • U-COP (Universal CPU Overheating Protection) — it's not necessary for AMD64 processors (it is activated by indirect signs instead of the thermal sensor in a processor)
  • BFG (Boot Failure Guard) — automatic restoration of the last good BIOS configuration in case of an overclocking failure.


Jumpers and switches Clear CMOS jumper  
Wake-up jumper at PS/2 and USB  
A set of jumpers to enable parallel operation of audio jacks on the rear and front panels  
In BIOS v2.58 from AMI Allows to disable specific CPU functions + K8 Cool'n'Quiet
Memory timings + CAS Latency, RAS to CAS Delay, Min RAS Active Time, Row Precharge Time, MA (1T/2T) Timing, Burst Length, Bank Interleaving, Flexibility Option
Memory frequency selection + Auto, DDR266, DDR333, DDR400 (you actually specify a multiplier to the HTT frequency)
HT bus setup + frequency (Auto, 200 MHz, 800 MHz, 1000 MHz) and capacity (8 or 16 bit)
Peripheral bus frequency control + PCI-E(PCIx3) = Sync (increase proportionally to the HTT frequency) or fix at 70—150 MHz at 1 MHz steps
PCI IRQ manual assignment -  
FSB frequency setup + 140—300 MHz at 1 MHz steps
CPU multiplier + from x8, at integer steps
CPU core voltage control + 0.800—1.550 V at 0.025V steps
Memory voltage control + Auto, Low, Normal, High

We used BIOS 1.00; later versions, available at the time of this review, just added microcodes of the new processors. The mentioned BIOS parameters are available in this version, but the viability of non-standard settings hasn't been tested.


Testbed configurations:

  • CPU: AMD Athlon 64 4000+
  • Memory: 2 x Corsair XMS3200 TwinX (DDR400, 2-2-2-5)
  • HDD: Samsung SP1213C (SATA, 7200 rpm, 8 MB buffer)
  • Video card: ATI Radeon X800 XT, 256 MB DDR
  • Power supply unit: FSP AX500-A
  • OS: Windows XP SP2

As the ASRock 939S56-M is the first model on SiS756 that we tested, we cannot possibly compare its results with other representatives of the chipset. But as we remember well that the performance of motherboards for AMD64 does not depend on a chipset (to be more exact, only periphery and, perhaps, video card's performance), we can safely compare our today's budget model and the top motherboard ECS KN1 Extreme on nForce4 Ultra.

Test ECS KN1 Extreme (NVIDIA nForce4 Ultra) ASRock 939S56-M (SiS756)
Archiving with 7-Zip, min:sec 7:32 7:32
Archiving with WinRAR, min:sec 2:09 2:08
MPEG4 (XviD) encoding, min:sec 5:06 5:09
Processing images in Photoshop, min:sec 31:08 32:32
Unreal Tournament 2004 (Low@640x480), fps 86.1 84.5
Unreal Tournament 2004 (Highest@1600x1200), fps 81.2 78.9
Doom3 (Low@640x480), fps 116.6 127.6
Doom3 (Highest@1600x1200), fps 59.8 59.8
FarCry (Low@640x480), fps 178.6 183.8

As you can see, the two motherboards on absolutely different chipsets demonstrated very close results in 2D. It's only natural, considering that this ASRock motherboard allows to choose DRAM Timing mode and specify all main memory timings in BIOS Setup. As we already mentioned before, nForce4 chipsets behave strangely when working with 3D graphics, but the results in this case are similar anyway. Having experimented with additional memory parameters (listed in the table above), we noted a performance drop triggered by disabling Bank Interleaving and enabling Flexibility Option (we haven't determined what this option really does), while changing Burst Length had no effect on the results. Note that we carried out these express tests only in synthetic (stress) RMMA test, so real applications may act differently.

To sum it all up, the ASRock 939S56-M motherboard proved itself a fast model with some modern features, unassuming functionality and bundle. In return, this model comes at an extremely low price. No doubts, this product will be very popular.

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

The motherboard is kindly provided by the manufacturer

Vladimir Senchihin (sench@ixbt.com)
November 1, 2005.

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