Thermal Transfer



Thermal Conductivity: For our purposes a more appropriate definition will be Heat Transfer by Conduction. This is the transfer of kinetic energy (heat) through a material without any movement of the material. The rate at which heat is transferred through a material depends upon the temperature gradient and the conductivity of the material itself, for example copper possesses higher thermal conductivity then aluminum. Another term pertinent to this section; Specific Heat is defined as the amount of heat required to change a particular unit of matter by one degree in temperature.

The RX-K8 is made of copper which offers the most cost effective balance of specific heat and thermal conductivity. In order to take full advantage of copper's thermodynamic properties the material must be formed and constructed in just the right shape. Many ingredients combine for just the right thermal recipe, base-plate thickness, surface condition, number of cooling fins. Cooling fins must be formed at a specific thickness, length, width and surface texture to take full advantage of the air passed over them to dissipate heat effectively. Fins are not the only surface shape used for this purpose, a few HSF manufacturers including Alpha and Swiftech made extruded pin design HSF famous with their PAL8045 and MCX-478V (.pdf) respectively. Fins seemed to be the surface structure of choice over the last few years and Thermaltake's RX-K8 features 46-machined surface cooling- fins press-fitted into a copper base.



Heat is kinetic energy or the collision of molecules and as explained above since the heatsink is a fixed object it doesn't move, nor do the molecules it is composed of except in relation to each other. In other words rapidly "vibrating" copper molecules do not "travel" from the base-plate to the fin surface, what does travel is the "energy" as each molecule collides with its neighbor. Since heat usually travels from a higher temp region (faster vibrating molecules) to lower temp region (slower vibrating molecules) heat from the CPU is conducted through the base plate, up through the fins where forced air has "cooled" these fins, the process is perpetual whether or not the fan is on or not.



A critical aspect of forced convection cooling (air) is a concept known as laminar air flow. Read any number of PC-forums or reviews pertaining to cooling and you'll find the term kicked around more then a Hacky Sack at a Hemp convention. The term is often used out of context as Laminar airflow is one of two types of airflow interaction (or molecular interaction) as it passes over an object. Air molecules closest to the surface tend to adhere to that surface, air molecules in motion above the first "stagnant" layer colliding with it travel slightly slower. As these layers rise further away from the surface their speed increases as resistance decreases. This pattern continues until the air-stream is uninterrupted. Problems can arise where the air-molecules come in contact with a surface as these act as a Boundary Layer. Semantics behind the name boundary layer are apropos since this layer can have a deleterious impact on thermal transfer. The chart below summarizes much of this explanation.



The theory behind cooling fins is very simply to provide as much surface area as possible in the least amount of space. While this statement might seem antithetical it explains why the fins are placed so closely together, often just a few mm's apart. The unit is svelte compared to some of the LGA-775 behemoths weighing in at 530gr to 938gr (or 2lbs). On the DFI LAN Party these usually require through mount hardware to safely secure the unit to the mainboard and of course this requires removal of your mainboard which basically involves disassembling your entire system. The mounting hardware as mentioned on the previous page uses the stock retention mount (RM) making installation an ease.



From the photo above you can see DIMM-1 looks to be close, this is an attribute of the LAN Party UT Nf4 mainboard layout and not the RX-K8 which would be considered svelte compared to today's monsters. Turning our attention to the photo below the heatsink leave plenty of room for the memory and uncommonly tall sticks such as Corsair XMS Pro or XMS XPert should be fine.



The RX-K8 delivers what is commonly referred to as secondary air-flow. Thermaltake didn't set out to reproduce a cooler such as Thermal Integrations Dr. Thermal looking at the T.I.T.I.'s base-plate below the CPU contact area or "foot-print" is a minimalist design. Where most heatsinks have a large rectangular base-plate into which the fins are pressed, Dr Thermal minimal foot print allows forced air from the fan above to freely flow down onto the socket area and the devices in close proximity to the socket.



Comparing Dr. Thermal above, to Thermaltake below, we might say the former is a design in which aerodynamics plays a greater role in the heat transfer process while Thermaltake uses a straight forward approach with the exception of its inverted fan for silent cooling.