Monday, February 20, 2006

P2-AE2: Silencing Update

Simply using some software utilities, it was very easy to get the Pundit to run very quietly without getting too hot. Using CrystalCPUID to replace Cool'n'Quiet, the Sempron 3000+ was undervolted:
-- State Multiplier VCore
-- IDLE 4x 1.10v
-- LOAD 9x 1.20v
Speedfan was then used to control the fans, using a LOW setting to keep fan speed down, and a HIGH setting once temperatures got hot under load. The LOW settings was selected so that the fans were virtually inaudible over the spinning of the HDD. The HIGH settings were selected based on the highest fan speed before the ASUS fans clicking became apparent from a distance of 2 feet.
-- LOW : CPU Fan = 20% 700rpm / SYS Fan = 40% 1200rpm
-- HIGH : CPU Fan = 30% 1200rpm / SYS Fan = 60% 2100rpm

With an ambient temperature of 22C, the following system temperatures were recorded when the PC was idle in Windows, and when put under load with Prime95:
Idle --- LOW ----------- 29C 38C 42C
Load -- LOW ---------- 50C 48C 46C
Load -- HIGH --------- 43C 41C 43C

During the day, the system is inaudible at LOW and even with my ear within 2 feet, I have to listen very carefully to hear it over the ambient noise. At HIGH the system becomes audible, but the sound is smooth and not loud.
At night however, in a very quiet room even the slightest noise becomes apparent. At the LOW setting, the main source of noise is the spinning of the 2.5" HDD. The Samsung MP0402H used is actually a very quiet single-platter drive, rated idle noise at 2.2Bel and tested by SilentPCReview at 17dBA from a distance of 1m. I would say this is quieter than many notebooks found on the market today, and very close to my Mac Mini in which I installed the same HDD (the Mini having the slight advantage of a more enclosed case to help muffle the sound).

Both fans are setup to bring cool air into the case, with the hot air being forced out the side vents. Switching the direction of one or both fans did not improve the cooling. One problem with the ASUS fan was the extremely audible clicking especially at higher rpms. I tried setting the PWM frequency to the highest with Speedfan or using a rheostat fan controller but it didn't help.
The stock AMD fan seemed to be smoother, but when run at low rpms wasn't any better than the ASUS. The holes on the AMD fan didn't match up, but a little encouragement from a pocket knife made sure it fit nicely onto the heatsink. I also tried several other 70mm thin fans including a Sunon Maglev, but alas none proved any better than the ASUS fan.

Next thing was to try a 80mm thin fan. Despite it's high speed rating and dual ball bearings, the Zalman 80x15 fan is a very smooth fan that runs nicely at low rpms. No clicking or whining here. There was just enough room for a 80mm fan, but of course the mounting holes didn't match the 70mm sizing of the heatsink.

Well you know those millions of twist ties that come tied around the cables of every appliance/accessory, well here is a chance to recycle and put them and put them to good use. They handily allow the 80mm fan to be mounted securely onto the heatsink. They probably aren't extremely heat resistant, but they are tied to the heatsink mounting frame on the motherboard which shouldn't get too hot.
With the ASUS fan, I had to keep the rpms low to prevent the clicking from getting too loud, but with the Zalman it was only the wind turbulence noise once the cover was put back that limited the high setting. This allowed the HIGH fan settings to be significantly quieter than the ASUS fan, and overall temps ran cooler, notably the SYS temp by 5-6C.
Idle --- LOW ----------- 28C 33C 41C
Load -- LOW ---------- 52C 42C 45C
Load -- HIGH --------- 42C 35C 40C

Even at night, the HIGH settings were very quiet, producing only a soft whooshing sound. I tried to see if airflow could be further improved by adding the virtually silent Sunon 40mm, but unfortunately there wasn't space near the vents for even such a small fan.

For those curious about fanless systems, even with the case open and undervolted, the system temps would slowly rise to the point were it got too hot. However with just one 80mm Panaflo M at 5v and an open case kept temps at a relatively cool CPU 41C, SYS 35C, HDD 35C under load.

Well with the HDD being the main source of audible noise from here to a truly inaudible PC, we couldn't let it go without a try.
First attempt was to suspend the HDD, so none of the vibrations will resonate onto the PC frame. Here some rubber bands are used, but this is actually a poor choice as over time they tend to crack/cut/break especially in a hot enviroment; in anycase this is just temporary. Four rubber bands were wrapped around the bottom mounting screws,

strung through the chasis and held together at the top by a handy (recycled) twist-tie. Unfortunately the 2.5" doesn't really vibrate much in the first place, and this suspension didn't make any perceivable difference noise wise.

Next thought was to enclose the HDD and muffle the sound, but at the same time not let it suffocate in it's own heat. With the plethora of external notebook HDD enclosures available for as little as $5, this seemed like an easy solution. The aluminum casing would allow some of the heat to propogate out of the enclosed space and at the same time keep in the noise. The drive did actually run 2-3C cooler, but unfortunately there was no perceivable difference in the noise level (I should have known this from using those extermely audible external enclosures). Stuffing a soft cloth to close up the opening where the IDE cable passed did help dampen the noise very slightly, but also caused temps to rise 1-2C. Maybe a thicker casing or adding some acoustic dampening material to the outside? Will experiment more with this later...

The HDD noise is less noticable from the front of the case, so placing the system with the front facing you will help. Also with it's horizontal orientation, locating the Pundit on a tall shelf or on top of a counter may make it virtually inaudible with the slight insulation help from the furniture plus with it not being at ear level. I also thought of mounting it upside down to the bottom of the table, but wasn't quite ready to drill any holes in my desk.
From the fixed legs and thin width, the Pundit wasn't designed to be orientated vertically, although it can be done. Here it's put up on some tapes to let air out the downward facing vents. The temps were slightly warmer but still acceptable. If you choose this orientation, you should lean it against a wall or side of the table and preferably fix it to prevent it from tipping over.

(Photos removed for those with weak hearts)
Hoping to get better thermal performance, I attempted to replace the pre-applied thermal paste with some better performing Artic Silver/Ceramique, but found the heatsink stuck to the CPU and impossible to remove. If you change enough heatsinks/CPUs you may have had the gut-wrenching experience where upon removing your heatsink you find you have accidentally yanked out the CPU along with it (while the socket is still locked)! Well this time I had to forcefully do that as the only way to get the heatsink off (heating/cooling the CPU made no difference)!! Very fortunately no pins were damaged.
Even with the heatsink/CPU off the motherboard, I had a very hard time trying to pry the CPU from the heatsink, and when I finally managed, had to resort to some serious scraping to remove the remaining bits of thermal-super-glue. Shame on ASUS for using a substance closer to adhesive than paste, making it extermely difficult to replace a CPU on the Pundit without risking damage. If you plan on eventually upgrading your CPU in your Pundit, remove the pre-applied thermal-super-glue from the beginning and replace it with something like Artic Silver (non-adhesive type).
That being said, after all that work and scare, the temperatures were no different with the Artic Ceramique applied.

Next - Stealthed and Silenced

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