Quiet PC for Torrid Thailand

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TESTING & RESULTS

The tools used to stress test and burn-in this computer included:

Ambient room conditions were 18 dBA for noise and 21°C for temperature.

The system remained stable and generated no errors during 48 hours of continuous Prime95 testing, done simultaneously with one instance of CPUBurn. For some stretches, three of the stress programs — CPUBurn, Prime95 and 3DMark05— were run simultaneously in order to force the highest possible stress on the system and maximize demand on the power supply. The following table summarizes the results of the testing. Quiet Mode is the normal mode in which the system is meant to be used.

FRANK's PC TEST SUMMARY
Parameters
Quiet Mode
Cool Mode
Coolest
Noise (SPL, 1m from front of case)
22 dBA
28 dBA
36 dBA
Noise (SPL, 1m from back of case)
23 dBA
29 dBA
36 dBA
CPU Temperature, maximum
47°C
45°C
43°C
CPU Temperature, idle
27°C
28°C
26°C
GPU Temperature, maximum
49°C
45°C
42°C
GPU Temperature, idle
40°C
39°C
39°C
HDD Temperature, maximum
34°C
32°C
31°C
HDD Temperature, idle
25°C
23°C
23°C
Board Temperature‡, max
32°C
30°C
30°C
Board Temperature‡, idle
30°C
29°C
29°C
Idle system power draw
99W (AC)
99W (AC)
99W (AC)
Idle system power draw w/Cool 'n' Quiet
94W (AC)
94W (AC)
94W (AC)
Maximum peak system power draw
190W (AC)
190W (AC)
190W (AC)
Fans
Speed
Speed
Speed
Nexus 120 fan on CPU heatsink (Q-fan*)
600 RPM
1100 RPM†
1100 RPM†
Tricool 120 fan on back panel
700 RPM
1100 RPM
1700 RPM
Nexus 92 intake, upper
900 RPM
900 RPM
900 RPM
Nexus 92 intake, lower (Q-fan*)
1100 RPM
1550 RPM†
1550 RPM†

‡ Board temperature is one of three sensors on the motherboard picked up by Speed Fan.
*Q-fan is the thermal fan speed controller in the Asus motherboard.
†Q-fan turned off.

Quiet Mode: The thermal results are particularly nice. 47°C was the highest temperature seen for the CPU at any time during the testing. At idle, it's typically 27°C with Cool 'n' Quiet engaged. The hard drive typically sits at 25~26°C; it took a long time to reach 34°C using the check noise feature of Hitachi's Feature Tool.

Remember that the system will reside in northern Thailand where ambient temperature can reach 40°C. I know Frank has air conditioning, but still, this PC has to be able to withstand native conditions. So add 20°C to those numbers (the difference between my test room ambient and the 40°C anticipated maximum of Thailand): We get 67°C for the CPU and 69°C for the GPU. If the HDD was stressed as hard as I did, it would reach 54°C, which is high, but the chance of this happening is extremely remote. In normal use, I never saw the HDD temperature go past 28°C. If the ambient was 20°C hotter, it would still be under 50°C, which is a bit hot, but probably about the norm for most big-brand PCs. All of these temperatures are well within normal operating limits. Since the stress tests put more load for a longer time than just about anything anyone would run on this PC, the machine is probably over-engineered, thermally.

Cool Mode: Just as a check for thermal cooling, Q-fan was turned off so that both the CPU Nexus 120 fan and the bottom intake Nexus 92 fan were running at full speed. The back Tricool 120 fan was sped up to a point where is began to add to the overall noise; this turned out to be with the rheostat knob just below mid point. The overall measured noise rose to 30 dBA@1m. Overall airflow through the case was substantially increased. The stress tests were run again, and the results are compiled in the Cool Mode column in the above table. The CPU temperature maxed out at 45°C. The hard drive temperature dropped to 23°C at idle and 29°C maximum. The maximum GPU temperature also dropped 10°C, down to 57°C. Those are pretty amazing numbers.

Coolest: This was an extreme test out of sheer curiosity, with all the fans that can be controlled set to run as fast as they can. The only difference between this and the Cool Mode was the speed of the exhaust fan, which went up from 1100 RPM to 1700 RPM. Noise jumped to 36 dBA@1m, the sound being almost entirely broadband "wooshing". Cooling of the CPU improved a bit, but not much else changed. It appear that the under the test conditions, the airflow of Cool Mode had already brought temperatures down as far as they could go. With higher ambient temperatures, I would expect bigger differences between all three of these settings.

PSU TEST

In late 2005, Antec NeoHE power supplies came under much criticism for incompatibility with many motherboards, including the Asus A8N-SLI Premium motherboard used here. The original PSU in the P150 used here did not work with this motherboard, although it worked with many other motherboards. It was replaced with a recently released revised NeoHE-430 that's supposed to be free of previous problems, and sailed through 48 hours of continuous stress testing (at 155W~190W AC load). Still, I decided to give it yet another round of tests: Over a period of 2 days, it was booted into Windows, then turned off and back on almost immediately as often as I could remember to do it (while I went about my other work). In all, I would guess it remained on nearly 48 hours and was cycled on/off/on at least 100 times. No error was seen in this ad hoc "test".

I will not cover the performance of this computer. The performance of an AMD Athlon64 X2-3800+ processor is well documented, as is the motherboard. The graphics card is fast, probably faster than Frank really needs right now. Suffice it to say it is much faster than my own main machine.

ACOUSTICS

This PC is very quiet, just above the threshold of my hearing from a couple meters away in a room ambient of 18 dBA (at 1:00 AM). From three meters distance, it's hard to decide whether I can hear it. At four meters, I definitely cannot hear it. The main sound character is a low level "wooshing" broadband noise. The computer is as quiet as the main Intel P4-2.8 / dual-HDD rig I run under my desk. The character of the sound is the same: Smooth, constant and unchanging, except for a touch of HDD chatter when it is seeking.

The 80mm fan in the PSU power supply, the 120mm Nexus fan on the CPU heatsink, and one of the two 92mm Nexus intake fan are all thermally controlled. They will speed up when things get hot. However, none of them ramped up even once during all of my testing. This is a very good sign, but I would expect that in >30°C weather, these fans will ramp up somewhat under load. They should!

The two manual fan controls on the back panel for the case exhaust fan and the VGA cooling fan assume some degree of hands-on participation in system cooling by the user. These fans could have been thermally controlled, but Frank would then lose direct control over the noise emitted by the computer. The price, of being a bit watchful during hot weather and turning up the fans if it's called for, is a small one.

CONCLUSIONS

The final challenge is to pack this PC up so that it will survive the air journey to Chiang Mai from Vancouver without damage. After much thought, I've decided to fill all the empty spaces in the PC with packing foam so that if something should get loose due to external shock, it simply can't go anywhere. I can't think of a safer way to protect the components. Frank will have to open it up and remove all the foam when it arrives there. He needs to check all the connectos anyway, especially the SATA drive cables which are so easy to dislodge.


Starting to stuff the PC with bubble packing material...

The P150 comes in a typical Antec retail box with top and bottom end caps made of Styrofoam. I will use those but go a step further and stuff all the empty spaces with Styrofoam pieces or chips. Then I'll double-box it in another carton so that if the box is dropped, it will be extra difficult to perforate it and do damage to the case.

It's been clear to me for some time that to make a quiet or silent computer, you need to take a holistic systems approach. But the execution has to be good as well; silence is in the details. All it takes a one small flaw for noise to jump up. Only Frank can tell us whether this quiet computer is a success in the long run. Maybe I can persuade him to send me an e-mail about it in a couple of months.

* * *

Thanks again to Canadian retailer NCIX for helping to source the components for this system.

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