AOpen's Core Duo Flagship i975Xa-YDG motherboard

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TEST RESULTS (continued)

4. Other Heatsinks

Since it is possible to use high performance aftermarket CPU heatsinks, we had to try a couple of our favorites. After all, the standard 478 retention bracket is one of the best aspects of this board for silencers.

A much-abused Scythe Ninja that's seen a lot of duty around the lab was installed. Care had to be taken with the clips, which apply a lot of pressure. If you are going to do this, we'd recommend installing the heatsink with really good access all around the CPU socket area. You'll need to be careful not to let the HS tilt on the CPU die while engaging the clips. A 120mm Antec TriCool fan was brought into service and set on low. It was the nearest fan at hand. It was simply set to rest on the stock NB cooler, with its fan unplugged. With the amount of airflow the 120mm fan can generate even on low, this seemed safe enough to try, as the NB would benefit from some of the TriCool's airflow. The fan was set to blow through the Ninja; it also provided cooling for the passive Asus graphics card.

A Scythe Ninja is ridiculous overkill for a 31W TDP Core Duo T2600, but it could be done, so it was.

A modified Zalman 9500 heatsink was also called into play. It's one where the stock fan, deemed a trifle too loud for us, was swapped out with a Nexus 92mm fan. Even with the screws employed for mounting, getting the 9500 on the CPU safely wasn't that easy. Again, we'd recommend installing the heatsink with really good access all around the CPU socket area. As with the Scythe Ninja setup, the NB fan was simply left unplugged. The Nexus 92 fan on the Zalman 9500 was simply plugged into the CPU fan header on the motherboard.

Zalman 9500 modded with Nexus 92 fan in similar setup as above.

The results, as shown in the table below, were predictable.

SPL ([email protected])
Scythe Ninja w/ Antec TriCool 120 @ low
CPUBurn OC'd*
Zalman 9500 w/ Nexus 92 fan @9V
CPUBurn OC'd*
*CPUBurn OC'd: These measurements were done with the CPU set to 2.6 GHz and 1.28V as before, running CPUBurn for >30 minutes.

The idle CPU temperature reported with either heatsink/fan is difficult to believe, but it's duly reported for the record. The temperature of the CPU at load was amazing with the Ninja, and only superb with the Zalman. The big fan used with the Scythe also kept the NB temperature way down as well, under all conditions. The much smaller, slow-spinning Nexus 92 used in the Zalman didn't provide as much airflow for the NB, and with the NB fan turned off, the temperature actually exceeded that of the stock cooler. Still, the difference was modest, and there was not even a whisper of instability throughout.

The acoustics also improved dramatically. With the Antec 120 TriCool on low, the general character of the sound improved to a smooth, very quiet whoosh. Now the Samsung notebook hard drive could be heard occasionally, along with the quiet 120mm fan in the Seasonic S12-430 power supply — very nice, overall. With the Zalman 9500 / Nexus 92, the fan is so quiet that it's basically inaudible from a meter. Whatever noise the sound level meter was picking up came not from the HSF but from the power supply fan and the residual ambient level of the room.

5. Audio Recordings in MP3 Format

Audio recordings were made of the test system with the three different HSFs. Keep in mind that the recordings paint only part of the acoustic picture. The microphone is within 3-4" of the primary noise source, and as a result, they tend to exaggerate differences (with good audio playback gear), much as if you placed your ear to within a few inches of the actual sound source. This is intentional, it's meant to help you examine the noise the way we do in the lab.

AOpen i975Xa-YDG test system with stock HS fans: 25 [email protected]
The first eight seconds have both HSF running. The next eight seconds are with the CPU fan stopped. Then it's with the NB fan stopped. Then we have both fans stopped, and what you hear is the background noise of the Samsung 2.5" notebook drive. Finally both HS fans are allowed to ramp up again.

AOpen i975Xa-YDG test system w/ Scythe Ninja + Antec TriCool 120: 22 [email protected]

AOpen i975Xa-YDG test system w/ Zalman 9500 + Nexus 92 fan: 20 [email protected]

Reference: Nexus 92mm case fan @ 5V (17 [email protected]) Reference


These recordings were made with a high resolution studio quality digital recording system. The hard drive was placed on soft foam to isolate the airborne noise that it produces; recordings do not take into account the vibration noise that hard drives produce. The microphone was centered 3" above the top face of the hard drive. The ambient noise during most recordings is 18 dBA or lower.

To set the volume to a realistic level (similar to the original), try playing the Nexus 92 fan reference recording and setting the volume so that it is barely audible. Then don't reset the volume and play the other sound files. Of course, tone controls or other effects should all be turned off or set to neutral. For full details on how to calibrate your sound system to get the most valid listening comparison, please see the yellow text box entitled Listen to the Fans on page four of the article SPCR's Test / Sound Lab: A Short Tour.

All this leaves little doubt that that 478 heatsink retention bracket is totally worthwhile on this board for any silencer. It's also clear that for very little additional cost, AOpen could do much better than the small all-aluminum CPU and NB HSFs they're supplying on this board. The bigger challenge is for noise-conscious gaming users of this board: How to cool two hot graphics cards quietly enough so that the acoustic advantages of the cool-running Core Duo CPU and the big 478 heatsink capability are not lost.

6. External SATA Functionality

The hot-swap capability of the External SATA connection was tested with a formatted WD Caviar SE16 500GB drive and an unformatted WD Raptor 150GB drive. In both cases, the eSATA featured worked perfectly. As soon as the cable connected the HDD to the board, the external drive was recognized correctly, allowing it formatted if necessary, and access was provided immediately to the formatted disc. The AC power demand rose by 10~11W when the drives were connected. Note that this is not a standard eSATA connector; it is an adaptation of internal SATA. "Real" eSATA external drives use a slightly different connector, are self-powered (with their own AC power supply or adapter) and do not need power from the board. The question asked earlier is worth repeating: How many users will simply use a bare hard drive outside the case?


The AOpen i975Xa-YDG is an interesting product. On the one hand, it is designed solely for use with Intel Core Solo / Duo processors, which run exceedingly cool, thus enabling very low power consumption. On the other hand, it supports ATI's dual-graphics card Crossfire technology, which, if employed with high-end cards, can mean power demand approaching 250W (in DC power) for the video subsystem. In fact, aside from the processor, the i975Xa-YDG allows a plethora of high power devices to be run off it, which gives it something of a schizoid personality, in our view. What is the point of employing a CPU that draws under 35W if the rest of the system is allowed to draw >300W? It is an approach that's almost the antithesis of AOpen's own MiniPC or the Core Duo based LCD panel iMacs from Apple.

Apparently, SPCR's point of view is not the norm, as this motherboard seems very popular among well-heeled Japanese aficionados. We have to assume they have deep pockets for their hobbies, as the steep ~US$300 price of this board is only one of the many items needed to build a system around it. Core Solo / Duo processors are also not exactly bargains at this time; a T2600 fetches upwards of US$500.

Nevertheless, the AOpen i975Xa-YDG does what it does very well. Although the stock heatsink/fans are not that quiet, it is easy to replace them with much better aftermarket coolers. The sheer range of features is probably enough to attract many buyers, and no doubt there are gamers among the SPCR audience who will eagerly seek out this board. The combination of Core Duo performance and overclocking potential means the AOpen i975Xa-YDG is arguably the most power efficient dual-graphics card capable motherboard for extreme gamers today.

Much thanks to AOpen for the i975Xa-YDG review sample.

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SPCR Articles of Related Interest

AOpen i915Ga-HFS ATX Pentium M Motherboard
17" Apple iMac: The Official SPCR Review
VIA EPIA EN12000E: Today's most efficient CPU & mainboard
Desktop CPU Power Survey, April 2006
Asus A8R32-MVP Deluxe w/ATI CrossFire Xpress 3200 Chipset

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