Thermal paste? Yes, which one and where?
First, let’s take a look at the impression of the opposite side, i.e. the cooler. And we realize that something is not quite right with the thermal paste already applied by the cooler OEM. There was something…
Right! The cooler of the RTX 4080 TUF Gaming is more or less the second version of the RTX 4090 and we can also see that the chip of the RTX 4090 is upright, whereas the RTX 4090 has been rotated. The chip just fits and a relatively large amount of a relatively thin and rather inferior paste has been used and then positioned inappropriately! The old clothes from the big brother can certainly fit, but it really isn’t ideal, even if quite a lot has been squeezed out even on the narrow sides.
Now let’s take a look at the imprint on the GPU and be shocked. While the paste has already bled out and torn open in a relatively central area (you can recognize it by the lighter color and finer grain), the rest is floating in silicone – at least where there was paste in the first place. This is an inferior product and not even the dregs of the waste. You simply can’t sell something like this!
The matrix of the paste is already dissolving and I would refer you to my basic article on thermal conductive pastes at the end of this page. Under the microscope, it looks really bad. We can see that the silicone happily runs away and leaves the larger filler particles (AL2O3) behind, while the finer zinc oxide (ZnO) is washed away with it. As a result, it is missing as a gap filler between the coarser particles, just like the silicone. Sorry, but this should not be used!
I then looked for a closed area at the edge where the excess paste was squeezed out. As it was not exposed to any pressure and only to significantly lower temperatures, it is still quite easy to deduce the original condition. There is almost 15% silicone (I have simply combined all the components of the silicone into one term and one final value, so it is not the pure silicon content). The ratio of 70:30 between corundum and zinc oxide is perfectly acceptable, but the paste is far too fluid and does not have a solid matrix as a base. Either the mixing was poor or they simply cut costs. Neither is acceptable, sorry.
If you measure the surface, you can hardly see a noticeable hump, so the chip cannot have been the problem. A good paste easily compensates for such a small misalignment!
And where does the hotspot come from?
The great thing about the VHX 7000 from Keyence is the built-in “AI”, which makes it possible to recognize and separate complete surfaces based on their properties and also to calculate their areas and the respective proportion of the total area. The areas marked in red (and I was very generous and chose very small tolerance ranges) show that over 21% of the chip area is without contact to the heatsink and therefore also without cooling. If you set the areas a little more generously (and more practically), this is already 25% of the chip area, i.e. a full quarter! There’s no need to explain why this leads to snatching breathing and fan noise. It’s a logical consequence!
This brings me to the conversion and the counter-test. Which brings us to the times of day. Please turn the page one last time!
ASUS TUF Gaming GeForce RTX 4080 SUPER OC, TUF-RTX4080S-O16G-GAMING, 16GB GDDR6X, 2x HDMI, 3x DP (90YV0KA0-M0NA00)
Lieferzeit 3-6 Werktage | 1219,99 €*Stand: 16.05.24 19:30 | |
Onlineshop: lagernd, Lieferung 2-3 WerktageFiliale Berlin, Filiale Dortmund, Filiale Düsseldorf, Filiale Hamburg, Filiale Hannover/Laatzen, Filiale München, Filiale Stuttgart: lagernd (keine Online-Reservierung möglich)Stand: 17.05.24 01:13 | 1273,43 €*Stand: 17.05.24 01:16 | |
Lagernd | 1273,73 €*Stand: 17.05.24 03:13 |
KFA2 GeForce RTX 4080 SG (1-Click OC), 16GB GDDR6X, HDMI, 3x DP (48NZM6MD6LSK)
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