Test Configuration
- ASUS A7V266
- AMD Athlon XP1900+ at 1715 MHz (12 x 143 MHz; 1.84V)
- ASUS V8200 GeForce3 Ti500
- 1 x 256 MB Muskin High performance
- IBM DTLA 307020 20 GB HDD
- Pioneer 12 x DVDROM
3Com905c 10/100T Ethernet adapter
Windows 98 (First Edition)
The candidates
Thermal Pads
Click on image for more details
Most heatsink - fans are still shipped with the standard thermal pads but regardless of how advanced they may seem, they do not yield the thermal transfer of any "grease" compound. In addition, they can be used only once. The easiest way of avoiding any problems with these pads is to remove them altogether. There are different ways of doing that, the most efficient solution I have personally found is ProLine hand-cleaning paste which is available in any auto part store. Just put on a solid splash, let it soak in for a few minutes and rub off the pad with the finger tip (or nail). Wipe off any possible residue with a moist paper towel and you are in business. ProLine is also an extremely efficient remover of Arctic Silver or similar components smeared over the CPU surface. An old toothbrush will take care of even the hidden corners and afterwards the CPU can be rinsed off under running water without problem (unless it is cracked).
Thermal Compounds
- Arctic Silver
- Arctic Alumina
- SIL-MORE Silicone compound
- Stars 700 Silver Grease
- RadioShack Heatsink Pen 64-4342
In short, neither of these compounds really provides any realistic thermal advantage over the others, temperature differences are in the noise and while Arctic Silver and Arctic Alumina may run 0.5 centigrades cooler than the white gunk, the difference is not significant enough to warrant their use. There are other issues though that do favor the use of one over the other component.
 
Some of the most common transfer compounds using either silicone as base or other, non-creeping substitutes. Click for more details.
The most important issue in terms of long term stability is that the compound stays exactly where it was over an extended period of time. Silicone-based compounds have been found to "creep" over time, that is, they move around, leaving bare areas which then cause local hot spots on the CPU. Interestingly, the oldest compound used here, I bought it about 3 years ago (RadioShack Heat Sink Pen), states in bold letters that it is silcone-free.
Some manufacturers state that there are up to 5 centigrade differences between different components. There is a possibility for this to happen but only if the components are used in the wrong fashion. The most commonly made mistake is that heat transfer components are used in excess and then act as insulators, particularly if their heat conductance is relatively poor. Just for illustration, here is a picture of what the bottom of any heatsink after careful removal from the CPU shoud look like.
Bottom of the Igloo 2310 after it was removed from the CPU. Note that there is basically no thermal compound in the contact area left and whatever residue is there is confined to the grain of the HSF surface or else the CPU markings. In fact, it is possible to read the most of the relief formed by the CPU markings. What this means is that there is 100% contact between the CPU and the HSF with little or no loss occurring because of insulation by the heatsink compound.
This is where some of the standard compounds fail, especially if they are reaching the end of their shelf life because their viscosity increases and they congeal to small lumps that cause uneven distribution. The manufacturers have reacted by composing their new compounds such that the original consitution has very low viscosity and can easily fill in all gaps without making bumps. One example is Arctic Alumina from Arctic Silver with its triple-phase consistency which gradually thickens over the next 20-100 hours of use before reaching its final phase that will no longer have a tendency to move.
| 