The effective thermal conductivity
What had already become apparent with the thermal resistance now comes in full broadside. Even if I once again have to celebrate the refutation of the fairy tale, because I have repeatedly written that you can hardly recognize or compare anything on the basis of the advertised PR thermal conductivity. Nevertheless, anyone who still believes that thermal conductivity is a constant value is very much mistaken. But I have already explained this at length in the basic article. If you have Rth, you don’t actually need λeff, i.e. the effective thermal conductivity. And the pure specification for the idealized bulk value is so far removed from reality that you always have to wonder about these figures. See the quotes on the first page. But the Thermalright TF8 is really awesome.
Of course, the whole thing is also shown again as a bar chart for the four most important layer thicknesses:
Apart from the fact that I also have the temperatures of the heater and the water, which are of no use to us because they always remain constant, I have my measurement setup with temperature sensors 1 to 6 (see diagram on page 2). These values can also be used to make some very interesting considerations.
GPU emulation
Let us first take the values of T3 and T4, which show us the two temperatures at the respective contact surfaces between which the paste is located. These curves are no longer completely linear, as the interface resistance also changes slightly. And we no longer calculate with 6 points, but only with 2 absolute values for the temperature difference instead of a gradient as withTTim, whereby the sample temperature remains constant. And what is the point of all this? The behavior is similar to that of a graphics card, which has to manage without an IHS and where the delta is usually measured between the substrate and the water temperature. This can be projected quite well, because I test the temperature difference on the two surfaces between which the paste is located. The TF8 beats them all with flying colors.
CPU emulation
Now I compare T1 of the reference with T1 of the gaming paste A. While the heater remains constant here, we already have sufficient thermal resistance in the copper reference block to simulate the CPU temperature and its differences with different pastes in comparison to the reference and depending on the layer thickness of the paste. It is precisely this variable evaluation that no test on a CPU can offer, because it is always individually different and therefore not really reproducible. But the TIMA5 test does. And the Thermalright TF8 is once again the measure of all things (so far) and is at least 2 Kelvin below the reference, which also corresponds well with the practical tests when the paste has been applied perfectly.
73 Antworten
Kommentar
Lade neue Kommentare
Urgestein
Veteran
1
Urgestein
Urgestein
Urgestein
Veteran
Veteran
Urgestein
Urgestein
Veteran
Urgestein
1
Urgestein
Urgestein
Urgestein
Urgestein
Urgestein
Urgestein
Alle Kommentare lesen unter igor´sLAB Community →