The ‘flipping’ of the AMD Radeon RX 7900 suggests that reference cards may have a problem with vapour chamber design.


Der8auer published an in-depth analysis of the Radeon RX 7900 hot spot temperature issue. He bought four cards to test the most commonly mentioned issues, such as the difference between horizontal and vertical GPU installation.

As it turns out, there is a distinction. GPUs will reach higher hot spot temperatures when installed vertically, according to the video, with each card tested in a 10 minute burn-in test. However, this is not the entire story.

In horizontal installation, A and B cards will begin to throttle 1 minute after the test begins. A quick comparison revealed that the Radeon RX 7900 GPU tested ran hotter in horizontal mode than in vertical mode. In horizontal mode, these cards were running at ‘well above’ 2000 RPM, whereas vertical mode was running at 1700-1800 RPM.

AMD Radeon RX 7900 XTX temperatures, Source: der8uaer


Der8auer created a special stand to test whether the cooler weight and gravity are to blame for the higher temperatures observed in horizontal mode. This test produced similar results when compared to the lack of cooler support, indicating that it is not an issue.

Similarly, disassembling the cooler and removing the support bracket that is in direct contact with the VRM did not improve the temperature. The YouTuber speculated that the stand offs’ height might have created a small gap, affecting cooler efficiency, but this simple test confirmed that this was not the case. He even went so far as to grind the stands on the main cooler part to reduce the gap between the GPU and the cooler, but this did not resolve the issue.

AMD Radeon RX 7900 XTX temperatures, Source: der8uaer


Another possibility was a vapour chamber issue. Furmark der8auer rotated the entire test bench while one of the tested cards was still running to see if the temperature had increased significantly. Even flipping the card again didn’t restore the lower temperature. The same problem was found with both modified and unmodified RX 7900 reference cards.

AMD Radeon RX 7900 XTX temperatures, Source: der8uaer


This left Der8auer with only one possible explanation: a vapour chamber design flaw. While it is not intended to be rotated, it suggests that the liquid inside the chamber may have difficulty recirculating after condensing (a vapour chamber is basically a large heatpipe). He claims that this could be a design or material selection issue, but he is certain that it is a vapour chamber issue.

AMD recently issued a short statement encouraging people experiencing thermal throttling to contact their support:

“We are aware that a limited number of users are experiencing unexpected thermal throttling on AMD Radeon RX 7900 XTX graphics cards (reference models made by AMD). Users experiencing unexpected thermal throttling of an AMD Radeon RX 7900 XTX should contact AMD Support.”

However, as Der8auer points out, this issue is now affecting a large number of users, and if the vapour chamber is the source of the problem, AMD may be forced to take drastic measures.

Source:  [der8auer EN] I was Wrong – AMD is in BIG Trouble ( YouTube – New Window)

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