Overclocking XFX Speedster MERC 319 Radeon RX 7800 XT BLACK Edition
There are some unique design features of the Radeon RX 7800 XT GPU that make the discussion of overclocking interesting. There is a nice review of overclocking nuances of this video card located here. As the article states, the Radeon RX 7900 XTX has two clock domains; a “shader clock” and a “front-end clock”. The Radeon RX 7800 XT is designed identically. Both clocks are integral in the graphic displayed. Both are dynamic and will adjust to the game’s demands.
Once again, we used the AMD Radeon Software Performance Tuning software to overclock the XFX Speedster MERC 319 Radeon RX 7800 XT BLACK Edition. In this software we are able to manipulate the “maximum GPU frequency”, the memory frequency, the power target, and the fan cycle. The voltage is maximized by default. The highest we could set the power target to was 15% over the default. Our final settings were 3050MHz GPU frequency, +250MHz memory frequency, +15% power target, and 50% fan cycle. The default settings are on the left.
Front End and Shader clocks
Here we see the dynamic results of our overclocking of the XFX Speedster MERC 319 Radeon RX 7800 XT BLACK Edition compared to the default. Taking into account the manual nature of the benchmark testing the results are nearly identical. The default Front End clock on average is 2956MHz and overclocked 2957MHz. The shader clocks are 2534 and 2535MHz respectively. These results account for the very limited success of overclocking this video card.
In testing the card we started at 2800MHz and incrementally increased the clocks to a maximum of 3325MHz. Interestingly, at 3050MHz we did see a slight increase in the clock speed in two of the 4 games used to test for stability. At 3325MHz the GPU Core voltage decreased slightly, instead of increasing to meet the demand. This may indicate some sort of power throttle. We chose 3050MHz to run our overclocks. The VRAM was increased +250MHz giving us a final 20.8GHz. We tried to go further but any increase was met with a green screen crash.
The above two graphs were created to demonstrate the behavior of the clocks across three frequencies we used for establishing our overclocks. This further emphasizes how close the clocks are in real-time and is most likely why the overclocking yields such marginal results. Both sets of data are tightly bunched.
We think that the behavior here, at least in the case of the XFX Speedster MERC 319 Radeon RX 7800 XT BLACK Edition is due to the already high +130MHz overclock. You can see in the charts the default Game Clock is running an average of 2956MHz on the Front End. Secondly, we did see some power throttling as we went over 3300MHz on the “maximum frequency” slider. This is very likely throttling the performance we see. You will see this demonstrated in the coming gameplay performance pages.
Of note, at 3050MHz the video card was very stable. The cooling was excellent and the GPU never exceeded 47c with the fans at 50%. The cooling fans are noticeable at this speed but are not at all annoying. The XFX Speedster MERC 319 Radeon RX 7800 XT BLACK Edition has a very competent cooling system.