iXBT Labs - Computer Hardware in Detail






ASUS M4A785G HTPC/RC Motherboard

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The board is based on the AMD 785G chipset with the AMD 785G Northbridge and the SB710 Southbridge.

The list of compatible processors published on the official website includes nearly all Socket AM2/AM2+/AM3 models. The board supports up to 16GB of DDR2-800/1066 RAM. Hard drive connectivity is 5 internal SATA/300 ports which can be used as RAID 0, 1 and 0+1. One more port is on the rear panel to provide eSATA functionality. In addition, the board has the following controllers:

  • Audio -- 8+2-channel VIA VT2020 HDA codec. The rear panel has an optical S/PDIF Out, and front speakers connectors are backed up by analog RCA's.

  • Gigabit LAN -- Realtek RTL8112L, PCIEx1.
  • FireWire -- JMicron JMB381, PCI, supports 2 x IEEE1394a ports, one on the rear panel.
  • System monitoring -- ITE IT8720F, supports automatic CPU fan speed management. The BIOS offers the Optimal, Silent, and Performance profiles. Both 3 and 4-pin fans can be controlled, but the mode -- DC or PWM -- needs to be selected manually.

We assessed the analog output quality of the integrated audio system in the 16-bit/44kHz mode using RightMark Audio Analyzer 6.2.3 and the ESI Juli@ sound card.

Line-Out (minijack)

Frequency response (40Hz to 15kHz), dB: +0.05, -0.40 Good
Noise level, dB(A): -92.4 Very good
Dynamic range, dB(A): 92.2 Very good
THD, %: 0.0039 Very good
THD + noise, dB(A): -81.7 Good
IMD + noise, %: 0.011 Very good
Channel crosstalk, dB: -94.2 Excellent
IMD at 10 kHz, %: 0.0096 Very good

Total score: Very good.

Line-Out (RCA)

Frequency response (40Hz to 15kHz), dB: +0.03, -0.23 Very good
Noise level, dB(A): -92.4 Very good
Dynamic range, dB(A): 92.2 Very good
THD, %: 0.0039 Very good
THD + noise, dB(A): -81.7 Good
IMD + noise, %: 0.011 Very good
Channel crosstalk, dB: -94.2 Excellent
IMD at 10 kHz, %: 0.0096 Very good

Total score: Very good.

The board scored good results in the objective tests. Besides, it sounded good, subjectively, especially for an integrated solution. Considering that the HTPC concept is primarily aimed at those who like movies and interactive entertainment, not audiophiles, we can say that ASUS has even provided some quality reserve. This isn't surprising though, because the company has been making decent sound cards for some time now.



  • CPU: AMD Phenom II X4 810
  • RAM: 2 x 2GB Apacer DDR3-1333 CL9 9-9-9-24-1T for Socket AM3 boards; 2 x 2GB GoodRAM PRO DDR2-1066 CL5 5-5-5-15-2T for Socket AM2+ boards
  • HDD: Seagate Barracuda 7200.10 (SATA, 7200rpm)
  • Graphics card: ATI RADEON HD4850, 512 MB GDDR3
  • PSU: AcBel ATX-550CA-AB8FB
  • OS: Windows Vista SP1 64-bit, Catalyst 9.2, latest chipset drivers


  • 7-Zip 4.65 x64
  • WinRAR 3.80
  • XviD 1.2.1
  • x264 r1129 x64
  • FarCry 2 (Ranch Medium)
  • Crysis (DX10, HOCbenchmark, VGA test, built-in demo)
  • Devil May Cry 4 (built-in benchmark)
  • World in Conlict (built-in benchmark)

To assess performance we measure time required to archive a 297MB set of 277 files of various types and convert a 636MB MPEG2 video using XviD and x264. We also measure frames per second in game demos. In FarCry 2 we run tests in 4 modes: low, medium, high and very high quality. The first three modes imply the aforesaid quality level, 1280x720 resolution, DX9 rendering, High Performance. The last mode implies: 1680x1050 resolution, Very High setting for both graphics and system, DX10 rendering. In Crysis we also use 4 modes at 1024x768 and 1280x1024 and run tests at Low and High quality in each mode. In Devil May Cry 4 we run two tests: 1280x720 (High DX9) and 1680x1050 (Super High DX10). In World in Conlict we run test in 4 modes: 1280x720 Low, 1280x720 Medium, 1680x1050 High, 1680x1050 Very High.

It's obvious which modes should be used with integrated graphics and which, with discrete graphics. Note that if a motherboard has no integrated graphics, performance tests are only used to check for serious layout or BIOS flaws and can be reduced to minimum. Vice versa, performance tests are indicative for motherboards with integrated graphics. And if a certain motherboard review lacks certain details, we might add respective test results to make up for it.

To assess capabilities of a motherboard and its BIOS, we overclock test CPUs (which ones depends on board's market segment) to a stable maximum with the help of Zalman CNPS9700 AM2 and Cooler Master Hyper Z600 coolers. At that we use all motherboard features, like CPU core voltage adjustments and, if needed, bus multiplier and clock adjustments (Hyper-Transport, CPU NB, etc.) For RAM we select a clock rate typical for this class of modules by adjusting its multiplier, or clock rate needed to maximize CPU core clock rate. The stability of an overclocked machine is assessed in Windows Vista with the help of AMD OverDrive stability test (all tests are run for 5 minutes). Note that since overclocking potential somewhat varies from one board to another, we are not focused on finding board's exact overclocking potential accurate to 1MHz. We just try to find out if a board hampers in CPU overclocking (due to insufficient voltage stabilizer power, etc.) and see how it performs in atypical modes, including automatic BIOS recovery in cases of overclocking issues (not requiring CMOS reset) and such.

Power consumption is assessed in the light mode (with a text editor running) and in the heavy mode (FarCry 2, high quality, 1280x720). At that we enable processor's standard power-saving features. Also, if a board has proprietary power-saving features, we examine their efficiency separately.

BIOS overclocking settings Availability Notes
Memory timings +  
Memory frequency + DDR2-667 ~ DDR2-1066
HT bus frequency (multiplier) +  
CPU reference frequency + 200-600 MHz
CPU multiplier + For cores and CPU NB
Advanced Clock Calibration -  
CPU voltage + 0.80-1.45 V (CPU)
0.80-1.45 V(CPU NB)
Memory voltage + 1.80-2.50 V
Graphics core frequency + 150-1500 MHz
Northbridge voltage + 1.10-1.20 V
Southbridge and HT voltage + 1.20-1.30 V

The adjustment ranges of the CPU multiplier and voltage, as well as the HT bus, provided by BIOS depend on the given processor. We publish results for our Phenom II X4 810. We used BIOS 0604 dated 1/10/2009.

All CPU overclocking options are provided in a single section, along with the resulting frequency values to be set for the chosen combination of reference frequencies and multipliers. The selection of options is just a bit poorer than regular found on mid-end boards. There is no Advanced Clock Calibration parameter which wouldn't be appreciated by those willing to experiment with unblocking of cores. The minimal memory multiplier corresponds to DDR2-667 which might interfere with overclocking by means of reference frequency, if you have memory modules not that stable at clock rate higher than 800 MHz. Besides, CPU voltage is limited by the moderate 1.45V.

CPU Phenom II X3 720 Black Edition (2.8 GHz) Phenom II X4 810 (2.6 GHz)
CPU frequency, MHz 3600 3250
CPU reference frequency (multiplier), MHz 200 (x18) 250 (x13)
Core/CPU NB voltage (according to BIOS), V 1.45/1.29 1.33/1.29
CPU NB frequency (multiplier), MHz 2400 (x13) 2500 (x10)
HT bus frequency (multiplier), MHz 2000 (x10) 1750 (x7)
Memory frequency, MHz DDR2-1066 DDR2-833
Notes Increased core and CPU NB multipliers Increased reference frequency, reduced CPU NB and HT bus multipliers

Still, the aforementioned limitations can hardly explain that poor overclocking by means of reference frequency. The standard processor potential was only realized in the CPU NB overclocking. However, the processor was decently overclocked with its multiplier unlocked. That set no records, but we hadn't expected any from a board like this. On the other hand, the voltage stabilizer didn't heat up much, so you can use this board with a moderately overclocked CPU. Besides, both Windows Vista and Windows 7 keep their standard power saving features in the overclocked mode, meaning you can leave Cool'n'Quiet enabled in BIOS and everything will work fine.

The feature that automatically loads BIOS defaults works reliably enough, so the fact that you can't save user profiles isn't that upsetting. (If pressing Reset doesn't help, you can turn power off and on on the PSU.)

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