Review: ASRock B85M-ITX Mainboard

This article about the ASRock B85M-ITX mainboard will summarize some information and test results I collected, including AC and DC power consumption figures. Please note this is not a classical review but more a test report focused on system efficiency.

Article Overview



A high-resolution photo of the B85M-ITX can be found on

Here are some detail shots of the ASRock B85M-ITX. The first image is a side-by-side picture with the H97M Pro4 on which I have done a seperate review.

The thermal image was made in idle state. Please note that the round “hotspot” is the BIOS battery which is not a heat source but just reflecting thermal radiation from the top.

There really are not many heat sources on the board, which is the reason why it is quite efficient as we will see later on. Some heat sources that can be identified:

  • RAM voltage regulator (bottom right)
  • Multi-phase CPU voltage regulator (top right)
  • Chipset heatsink (top left)
  • Two chipset voltage regulator MOSFETs (above BIOS battery)
  • Super-I/O and its surroundings (bottom left, hidden by SATA cable)


Component Inspection

This table summarizes the components used on the B85M-ITX as far as I was able to identify them. Please leave a comment if you can add something.

Manufacturer Name Description Remarks
Qualcomm Atheros QCA8171 LAN Controller on PCB bottom side
Realtek ALC892 Audio CODEC
Nuvoton NCT5573D Super I/O
?? ?? Power MOSFETs K03J5 3M4 61W3
Richtek RT9629B CPU VREG PWM Controller on PCB bottom side
APEC AP1280AMP DDR Bus Terminator
Nuvoton NCT3941S Linear Fan Controller CHA_FAN1


Test Setup

B85M-ITX Test Setup (including hardware, driver, software and UEFI configuration)

Component Description Price
Mainboard ASRock B85M-ITX $80 / 70€
CPU Intel Celeron G1840 $50 / 40€
Cooler Intel boxed
RAM Crucial DDR3-1600 4GB CL11 $45 / 40€
SSD SanDisk SDSSDP-064G-G25 $60 / 40€
Input Device Logitech Unifying Receiver   $8 / 10€
PSU LC-Power LC75ITX $45 / 35€


AC Power Consumption

Measurements include the AC-DC power supply, DC-DC converter (both LC-Power LC75ITX), mainboard and SSD. Absolute values include Logitech Unifying receiver, active HDMI (FullHD resolution) and Intel boxed CPU fan, but were measured with LAN cable removed and audio disabled in the UEFI.

AC Power
Power off (Deep Sleep) 0.2
Power off (WOL enabled) 0.8
Standby 1.2
Prime95 33.0
Idle 7.1
Relative to Idle
– Unifying -0.4
– Monitor -1.1
– CPU fan -0.4
+ LAN cable +0.7
+ Audio +0.4
Power meter: Profitec KD 302 All values in Watt [W]


DC Power Consumption

All DC measurements include the mainboard only (SSD is excluded). Absolute values include Logitech Unifying receiver, active HDMI (FullHD resolution) and Intel boxed CPU fan, but were measured with LAN cable removed and audio disabled in the UEFI.

Total 12VP4 3.3V 5V 12V -12V 5VSB
Power off 0.3 0.00 0.00 0.00 0.00 0.00 0.26
Prime95 27.9 22.73 0.40 3.74 0.64 0.00 0.36
Idle 5.1 2.18 0.39 1.57 0.64 0.00 0.34
Relative to Idle
– Unifying -0.4 -0.13 -0.27
– Monitor -0.9 -0.85 -0.08
– CPU fan -0.4 -0.35
– HDMI cable 0.0
+ LAN cable +0.5 +0.05 +0.47
+ Audio +0.3 +0.30
All values in Watt [W]


CPU Power States

For a low idle power consumption auf the whole setup, it is essential for the CPU to reach both C6 power state for both the core and the package. To make this possible, the right combination of hardware, BIOS settings and device drivers has to be used. Refer to the test setup PDF for details.

In my setup, the B85M-ITX reached C6 CPU core and package power states without any hassles as confirmed by ThrottleStop. The higher C7 state is not supported by the Intel Celeron CPU that was used for the tests.

The computer does run stable without any issues so far. However some remarks on specific quirks of the board:

  • When the CPU enters package C6, the mainboard will produce a quite audible chirp noise. This seems to mainly come from the ceramic capacitors of the voltage regulator around the CPU socket. The noise is independent from the used power supply.
  • With plugged-in LAN cable interrupts cause the CPU to leave package state C6 more often.
  • When the Atheros LAN chip is enabled in BIOS, the LAN cable has to be plugged in during boot or wake-up from standby; otherwise no CPU package state higher than C3 can be reached until the next reboot with a plugged-in LAN cable. Power consumption “without LAN” was measured with enabled LAN in BIOS and the LAN cable unplugged after boot.
  • UEFI option “CPU Integrated VR Efficiency Mode” is not available anymore for BIOS version 2.20 and newer. Power consumption with BIOS 2.20 was measured to be insignificantly less or equal to previous BIOS 2.10 with enabled VR Efficiency Mode.


LAN Performance

The onboard LAN controller is a Qualcomm Atheros QCA8171 which seems to be a passive solution, hence utilizing the CPU for network transfers.

The following data is recorded for a large file transfer over SMB. CPU utilization is measured with Process Explorer.

Transmitting Receiving
Speed 112 MB/s not measured
CPU total utilization 46%
CPU interrupt utilization 35%


Further reading


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