The launch of the new AMD graphics cards turns out to be less convulsive, and it is that if for some they are more than in conformity with what is asked of them, for others they are below performance. They are the ones who decided overclock your RX 7900 And they found an unexpected surprise. Loss of power. Why does this happen?
One of the most absurd controversies with the launch of the RX 7900 was its clock speed, all due to the fact that “news leaks” were talking about clock speeds above 3GHz. In defense of the Radeon manufacturer, we have to say that they never talked about those speeds, but the official improvement in efficiency per watt. In any case, these rumors have caused many users to overclock their next-gen AMD graphics cards.
Why does overclocking the RX 7900 reduce performance?
The increase in clock speed should mean an improvement in performance; however, on the RX 7900, overclocking can sometimes backfire. Let’s not forget that a GPU is a less complex chip made up of different parts with different speeds and power ranges. It is therefore common in designs to assign them different electrical domains. Think of it like rooms in a house with different switches that can be turned on and off.
However, things are more complex, since it would rather be to have light switches that can be set not to exceed a certain level of power consumption on the graphics card. Thus, they found that when this is done overclock an RX 7900 and the chip exceeds certain speed limits, the memory controller clock speed begins to drop. What we remember is in the small chips around the main one, in the case of the first GPU with chiplets.
The consequences of this? Easy, because graphics cards depend on bandwidth for their performanceAs the clock speed increases, its demand increases, but at the same time, the transfer rate between the GPU and the low memory eventually creates a bottleneck that reduces its working capacity. In the image you see below we can see how the fact of The increase in clock speed to 3281 MHz means a drop in memory speed to 1461 MHz. That is to say, 2.5GHz upgrade from 20Gbps to 12Gbps speed. In other words, a bandwidth reduced by almost half, from 960 GB/s to 576 GB/s.
What are the causes of all this?
Well at this point we can start to speculate but we believe that due to the high power 12+4 pin connector controversy that many have linked to NVIDIA despite being a standard PCI-SIG which AMD will use when the right time comes, and the associated problems. Which led the Radeon manufacturer to launch its RX 7900 with traditional power connectors.
All of this indicates that AMD’s most powerful GPU could go for a higher clock speed, but already within the parameters of needing a new connector. What makes us wonder if in 2023 they will have a possible RX 7950 XT ready with higher consumption, but also with much better performance. In any case, to release an improved version, AMD would not do so with the same chip, but with a paired version of it or, failing that, with an optimization. In any case, one of the things they need to improve is the curve between clock speed and voltage, which is worse than in the NVIDIA RTX 4090. Which indicates that overclocking is worse in the RX 7900 and, therefore, unless there are changes in this aspect, it would reach lower speeds.
