An all-aluminum heatsink that needs a very noisy fan to make it work. — Joe
OCZ Tech was nice enough to send us a sample of the OCZ Dominator 2. It’s an all aluminum unit with 46 “skived” fins.
Skiving is a new technique that literally shaves fins from the base material. The advantage is that there is no mechanical bond, such as soldering, between the fins and the base – it’s all one piece – effectively eliminating any thermal degradation due to the bond used between the two. Compared to a heatsink that mechanically crimps fins into the base, skiving can show markedly better performance.
Removing the top, you can clearly see the fin density – there are 46 fins.
Looking from the side, you will note the fins have a slight curvature – again I think due to the manufacturing process.
Looking down into it, you get a good feel for how densely packed the fins are. With this density, a low-flow fan will not do the job; the Dominator 2 offers two fan options – the YS Tech 40 cfm and the Delta 44 cfm unit (this has air straightening vanes in its base).
The fins are smooth on one side and have a “pebbly” grain on the other. I thing this is due to the skiving process.
The bottom shows fine polishing marks which are barely noticeable to the touch. If you run your fingernail over it, you can just about hear the sound of the ridges.
The clip is very user friendly – you do not need a screwdriver to engage the socket’s lugs. You grasp the lip between thumb and forefinger and move it over the socket’s lug – done!
Overall, this is about the most densely finned heatsink I have tested to date.
I prepared the OCZ Dominator by boring a hole completely through the base so I could epoxy a thermocouple above the CPU. The thermocouple is attached to an Omega HH23 Digital Thermometer. Ambient temps were measured with a thermocouple placed about 1 inch from the fan’s intake. I used Prime 95 to stress the CPU on an Iwill KK266+, Iwill BD133 (MBM temps are on-die) and Abit KT7. Arctic Silver grease was used in all tests. CPU Case Temp is the temp at that point where the CPU contacts the heatsink.
I tested the OCZ Dominator with the stock fan and a Delta 38. I also tested it on the CPU Die Simulator, as noted below.
|CPU Die Simulator|
CPU Die Temp
CPU Case Temp
|101 Watts, YS Tech 40 cfm|
|101 Watts, Delta 44|
CPU Case Temp
CPU Back Temp
|T-Bird @ 1400, Iwill KK266+, 40 cfm (72 watts)|
|T-Bird @ 1400, Iwill KK266+, 44 cfm (72 watts)|
|Duron @ 1000, Abit KT7, 40 cfm (63 watts)|
|Duron @ 1000, Abit KT7, 44 cfm (63 watts)|
|PIII @ 933, Iwill BD133u, 40 cfm (24 watts)|
|PIII @ 933, Iwill BD133u, 44 cfm (24 watts)|
C/W = Delta / CPU Watts
Interpreting C/W: For every watt the CPU radiates, the heatsink will cool the core by the (C/W x watts) plus ambient temp. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that the CPU temp will be 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.
The Simulated CPU Die Test gives results that are unaffected by motherboard influences – note that it closely corresponds to results we get using Iwill’s PIII in-die diode. It takes the Delta 44 to nudge the Dominator close to the “acceptable” range – 0.32 or better – for AMD CPUs. Considering the high fin density, you might expect better performance.
I think what’s going on here is that the Dominator is pushing fin density into an area where diminishing returns sets in very quickly. The more densely fins are packed into a given area, the more difficult it is to get airflow into the fins. In addition, the thinner the fin, at some point its ability to transfer heat is compromised.
Here’s a simple test that you can try to illustrate the point: Take a piece of aluminum foil 1″ x 4″ long. Heat one end and hold the other with your fingers. When I did it, I didn’t feel any heat while holding the tip of the foil in a gas flame. If you do the same thing with a piece of aluminum plate 1/16″ thick, you’ll get burned.
At some point, the interplay of fin density, fin thickness and airflow hit a point of diminishing returns, resulting in minimal performance gains.
The OCZ Dominator 2 needs a high airflow fan to make it work at its best. If you don’t mind the noise, then it’s not a bad price/performance buy. If you plan to use it with a low speed fan, you might be very disappointed with its performance.
Thanks again to OCZ Tech for sending the Dominator our way.