Very good performance, very loud noise — Joe
SUMMARY: Top rank performance with top rank noise.
The good guys at SIBAK were nice enough to send a sample of their copper core heatsink, the SIBAK AC-06-725TH. It features a copper core about 32mm in diameter surrounded by aluminum fins radiating out from the core. The copper core does not extend through to the top – it’s “buried” in the surrounding aluminum fins.
Removing the aluminum fan shroud
shows the fan bolted to the heatsink. Removing the fan and clip
shows the radial fin pattern; the groove is for the clip.
The fan is an Everflow model #T127025BU – a 70 x 25mm unit rated at 8.4 watts (do not use a motherboard fan header). At 12 volts, it spins at 6650 rpm with noise you would expect at this level – basically Delta 38 levels, although the fan’s noise includes a low whistling sound in addition to higher pitched sounds from the bearings.
I measured its noise at 69 dBA with a Radio Shack sound meter 8″ from the fan’s intake and normalized these readings. I then varied voltage to find performance at various rpms and noise levels.
The base
is flat and nicely polished – I could not feel any polishing marks on the copper core.
The clip is a little tricky – the rear clip is angled under the heatsink’s base, so you have to “feel” it into place. Once engaged, you have to use a screwdriver to mount the front clip. It’s fairly stiff and takes some pressure to engage the front clip.
In summary, an aluminum/copper cored heatsink with a very secure, though stiff, clip.
The SIBAK was first tested on the CPU Die Simulator which gives results that are unaffected by motherboard influences. I then tested it on an Iwill KK266+, modified to read AMD’s on-die diode, as an example of what users might see on their systems.
| Heatsink |
Die Temp
|
Ambient Temp
|
Delta
|
C/W
|
| SIBAK/7250rpm, 58 dBA |
45.6 C
|
21.2 C
|
24.4 C
|
0.32
|
| SIBAK/6650rpm (12v), 55 dBA |
45.7 C
|
20.0 C
|
25.7 C
|
0.34
|
| SIBAK/5700rpm, 52 dBA |
48.1 C
|
21.0 C
|
27.1 C
|
0.36
|
| SIBAK/3630rpm, 40 dBA |
55.2 C
|
21.3 C
|
33.9 C
|
0.45
|
| CPU/Motherboard |
CPU Die Temp
|
Ambient Temp
|
Delta
|
C/W
|
CPU Back Temp
|
| Palomino 1200, Iwill KK266+, 6800 rpm |
34.5 C
|
21.6 C
|
12.9
|
0.24
|
37.1 C
|
In-socket thermistor per MBM: 27 C
C/W = Delta / CPU Watts
Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.
Die Simulator results place the SIBAK, at 6650 rpm (12v) and high noise, in the top rank of heatsinks (Heatsink Ranking). Note that it takes a cutting fan speed almost in half from spec to get close to “acceptable” noise levels.
A very interesting design that turns in top rank performance, but once again, at the expense of your hearing.
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Tags: Cooling
