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As a general rule, motherboards do not consume a large amount of power, but
when they do, it's often the voltage regulation module (VRM) that
is at fault. A high wattage processor requires
a voltage around +1.5V. But the PSU supplies with only +3.3V, +5V,
and +12V to the motherboard. Therefore, the motherboard must convert one of these voltages into
+1.5V for the processor. The +12V line is almost always used to supply Vcore.
But, the conversion from +12V to +1.5V is not perfect. There are inherent losses
in this process, losses in the form of
heat. The less efficient the conversion, the more heat is produced, and the
more power is drawn by the system overall. Motherboards that can perform the voltage
conversion more efficiently run cooler and require less power under load. Typical
VRM efficiency runs between 70-85%, althought it's not linear, dropping at both high power and low lower levels.
Let's put that in perspective. Assume that a processor draws 75 watts under
load (a conservative estimate for many of today's processors). A motherboard VRM
that is 85% efficient will add >13 watts of additional heat to the system.
A 70% efficient motherboard will add double that amount!
Our review of the A8N32-SLI
Deluxe drew our attention to the fact that high end chipsets sometimes require
much more power than regular chipsets. In addition to the power lost to the
VRMs, the main I/O chips on the motherboard may also require a lot of power.
The ASUS A8R32-MVP Deluxe was tested against two other Socket 939 motherboards,
including an A8N32-SLI Deluxe. A common set of components was used so than any
differences in power consumption could be attributed to the motherboard alone.
The following components were used for the comparison:
- SilverStone Strider ST65F
560W power supply 78.4% efficient at 90W output, 80.7% efficient
at 150W output
- AMD Athlon 64 X2 3800+ Toledo core, revision E6. TCaseMax
reads the TDP as 65.6W, and the TCaseMax value as 63°C. Stock VCore is
- 2 x 512 MB OCZ PC3500 DDR SDRAM
- Scythe Ninja heatsink
cooled by a Nexus 120mm fan plugged into the CPU fan header
- AOpen Aeolus 6800GT DVD256MV cooled by a Thermalright V1-Ultra
undervolted to 5V
- Samsung Spinpoint P80 SP0802N hard drive
Yes, the Scythe Nija HS fits with room to spare.
Power was measured with an Extech Power Analyzer / Data Logger 380803
AC power meter
Processor voltage was monitored using SpeedFan
The ASUS A8R32-MVP Deluxe was compared against an ASUS A8N32-SLI Deluxe and a DFI LanParty NF4 Ultra D. The motherboards were tested in three CPU states:
- Idle, with Cool 'n' Quiet enabled
- Idle, with Cool 'n' Quiet disabled
- Under load, running two simultaneous instances of CPUBurn
POWER COMPARISON TEST RESULTS
ASUS A8R32-MVP Deluxe
ASUS A8N32-SLI Deluxe
DFI LanPartyNF4 Ultra D
Idle (No CnQ)
Load (2x CPUBurn)
*Processor Voltage for this test was 0.04V higher than
The results confirmed what we had already heard the A8R32-MVP is a pretty
cool cucumber. Unsurprisingly, it beats the A8N32-SLI easily, but it also managed
to achieve a 5W improvement over the DFI board, which is based on a regular
nForce 4 chipset.
Surprisingly, the DFI board consumed slightly less power under load, which
suggests that the VRM efficiency in the ASUS board was not as linear as it could
be. It also suggests that the VRM could have been affected by increasing heat and may benefit from a bit more airflow than the open test bench setup allowed. Even so, the 3W difference is not really significant from a cooling or energy efficiency point
of view; its performance in idle is much more important.
With power efficiency in mind, we used the BIOS to disable as many unneeded
peripherals as possible on the A8R32-MVP in hopes of cutting the power consumption further.
Unfortunately, none of our tweaking had any effect at all on power;
no matter how much we disabled, all of the power figures stayed the same.
If you're looking for a high-end 939 board that will run cool and
quiet, the ATI-based A8R32-MVP Deluxe is a pretty good way to go. At lower power levels, where
most systems spend most of their time, it consumed less power than either
of the nVidia nForce4 chipset boards that we looked at.
For most people, and silencers in particular, the high PCIe
bandwidth is a poor selling point because it is difficult to saturate a "regular"
chipset even with dual graphics cards. If CrossFire is not used, the extra
bandwidth is simply meaningless; no other application requires anything near
that much bandwidth.
eSATA port, the extensive BIOS options, good power efficiency, epecially at lower power levels, and passive cooling seem the most compelling features for a noise-conscious buyer. With socket AM2 just at the launching pad, the A8R32-MVP Deluxe may be just about the most advanced 939 board we'll see from Asus.
The bottom line is that if you have an exceptional set of components already picked out or planned around a hot socket 939 processor, the A8R32-MVP Deluxe can probably go a long way towards
ensuring that the system stays stable, well cooled, and quiet.
* Low power chipset
* Latest and greatest ATI chipset
* Simple but effective passive cooling
* eSATA port on rear panel
* Adjustable everything in the BIOS
* Metal backplate for secure heatsink mounting
* Fan controller is flexible and doesn't warble
* Firewire port requires PCI bracket
* No negative offsets for CPU Vcore
Much thanks to ASUSTeK
for the opportunity
to review this motherboard.
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Articles of Related Interest
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this article in the SPCR Forums.