iXBT Labs - Computer Hardware in Detail






ASRock K8 Combo-Z Motherboard
Based on ULi M1689 Chipset
for AMD Socket 754/939 Platforms

ASRock continues to develop the concept of motherboards with two CPU sockets. Another Combo series motherboard is ASRock K8 Combo-Z. This model combines two CPU sockets on a single PCB (Socket 754 and Socket 939). The question is: "Can you assemble a dual-processor computer based on this product?" This question is answered in the motherboard manual: you cannot, because you have to use jumpers to switch between the processors. When one socket is enabled, the other one is correspondingly disabled.

K8 Combo-Z is a low end device, so it cannot boast of a "gentleman set" of functions that high end motherboards possess. But some points are still a pleasant surprise. For example, integrated eight channel audio controller based on AC'97 codec Realtek ALC850 supporting 7.1 audio systems.

Unfortunately, two sockets do not mean dual processors.

The PCB layout is not very good. Though this model has impressive dimensions (305x245, full-size ATX, nine-screw mount), PCI and AGP slots are very close to IDE connectors because of the specific design. This makes it rather inconvenient, when there are long PCI or AGP cards installed. The 3-phase switching CPU voltage regulator, which is near the 939 socket, uses four 3300 uF capacitors and four 1500 uF ones. And the voltage regulator near the 754 socket incorporates four 3300 uF capacitors and several ones of a lesser capacitance.

This motherboard is based on a new single-chip core logic from ULi – M1689. K8 Combo-Z is the second model on the market, which is equipped with this chip (the first motherboard was Albatron K8Ultra-U Pro). Like in Albatron, the inexpensive solution from ULi has a positive effect on the overall price of the product. Combo-Z also supports a safe overclocking function (Hybrid Booster), which is good news for overclockers.

System monitoring (Winbond W83697HF)

  • CPU voltage, +3.3 V, + 5 V, +12 V
  • RPM of 2 fans
  • Processor and motherboard temperatures
  • It supports automatic shutdown at overheating.

Onboard ports, sockets, and connectors

  • Processor sockets (Socket 754, Socket 939)
  • 2 x DDR SDRAM DIMM (DDR 266/333/400 up to 2 GB) for Socket 754
  • 3 x DDR SDRAM DIMM (DDR 266/333/400 up to 2 GB) for Socket 939
  • 1 x AGP 1.5 V (with a latch)
  • 2 x PCI (2.2)
  • Power connectors: standard ATX and 4-pin connector for 12 V
  • 1 x FDD
  • 2 x IDE (Parallel ATA 133, up to 4 devices)
  • 2 x SATA (Serial ATA) supporting RAID 1/0/JBOD
  • 2 connectors for a bracket with 2 additional USB (2.0) ports
  • Game-port connector
  • 1 x CD/DVD audio connector
  • 2 x fan connectors (both with RPM control)

Back panel (left to right, blockwise)

  • PS/2 mouse and keyboard
  • 1 x LPT (ECP/EPP) and 1 x COM port
  • 2 x USB (2.0)
  • 2 x USB (2.0) and RJ-45 (Fast Ethernet)
  • 3 x Audio (Central/Sub, Rear, Side)
  • 3 x Audio (Line-in/Line-out(Speaker Out)/MIC)

Package Contents

  • Box: standard design box
  • Documentation: a motherboard guide in seven languages, a poster with brief instructions on installing SATA HDD
  • Cables: 1 x SATA, 1 x SATA with a power converter, 2 x ATA 66/100/133 and an FDD cable
  • ASRock 8CH I/O Shield
  • CD with software


  • ASRock U-COP – protects a processor from overheating
  • Boot Failure Guard (B.F.G.) – restores good settings after an overclocking failure
  • Supports Cool’n’Quiet from AMD.

Integrated Controllers

  • 8-channel audio, based on AC'97 Realtek ALC850 codec supporting 7.1 ch audio with front audio I/O jacks
  • LAN, based on the Realtek RTL8201 chip supporting 10/100 Mbit/sec (Fast Ethernet)

The integrated audio quality was tested in 16bit, 44 kHz using the RightMark Audio Analyzer 5.4 test application and the Terratec DMX 6fire sound card:

Frequency response (from 40 Hz to 15 kHz), dB:
+0.18, -1.12
Noise level, dB (A):
Dynamic range, dB (A):
THD, %:
Intermodulation distortion, %:
Channel crosstalk, dB:
Very good
IMD at 10 kHz, %:

General performance: Good (details).


Jumpers and switches Clear CMOS jumper
Jumpers to enable system wake up on USB devices
A set of jumpers to switch between Socket 754 and Socket 939
PS/2 keyboard power jumper
From AMI Legal BIOS Memory timings
Memory frequency selection DDR 266/333/400
AGP voltage control
PCI bus setup
AGP bus setup
AGP and PCI frequency divider setup
PCI IRQ manual assignment
FSB frequency setup 200-300 MHz at 1 MHz steps
CPU multiplier x4-x11
CPU core voltage control 0.825-1.550 V at 0.025 V steps
CPU voltage control 5%, 10%, 15%
Memory voltage control
Chipset voltage control Auto, 1.5 and 1.6 V
HT bus frequency control 200/400/600/800/1000 MHz

Preliminary test results

Testbed configurations:

  • CPU: Athlon 64 3400+ (Socket 754)
  • RAM: Corsair CMX512-3200XL x 2 (DDR400, 2-2-2-5)
  • HDD: Samsung SP1213C (SATA, 7200 rpm, 8 MB Cache)
  • Graphics: ATI Radeon 9800 Pro, 256 MB DDR
  • OS: Windows XP SP2

ASRock K8Combo-Z
7-Zip archiving
RMMA, reading, MB/sec
RMMA, writing, MB/sec
DivX encoding
Photoshop CS script
UT 2004 (800x600x32)

Subjective impressions

You can hardly expect extraordinary results from motherboards within this price range, but this is justified by the money spent on them. According to test results, ASRock K8 Combo-Z takes the third place among the video cards with the 754 socket we already reviewed. But the advantage of Albatron Ultra-U Pro and ASRock K8Upgrade-760GX is certainly not that large to play a pivotal role in your choice. Especially as we look into the future – ASRock K8 Combo-Z has a great potential of further usage in comparison with Albatron due to its second CPU socket (Socket 939). And it's quite obvious that the second socket is much better implemented in K8 Combo-Z than in K8 Upgrade. ASRock K8 Combo-Z has been designed for those who buy inexpensive AMD Sempron or Athlon 64 2800+, 3000+ processors (for Socket 754) today and then, in a year, will upgrade them to more powerful Athlon 64 3800+ or FX-53 processors (for Socket 939). It's quite a convenient solution in terms of price and quality, because K8 Combo-Z is currently one of the cheapest motherboards for Socket 939 processors. Besides, this model delivers from the problems connected with CPU upgrades and the transition to a new processor socket. Though only time can show how much such universal motherboards will be needed.

But irregardless of the fate of K8 Upgrade and K8 Combo, it's good that such products are manufactured. It means that not all engineers in R&D departments of motherboard manufacturers are in the groove of "conveyor design", sometimes they create motherboards "for their own satisfaction". Their results are another story, even the fact that such motherboards exist is good news.

The design of both models obviously deserves our "Original Design" award.


Vladimir Senchihin (sench@ixbt.com)
Stanislav Garmatiuk (nawhi@ixbt.com)
March, 2005

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