Overclocking SAPPHIRE NITRO+ RX 7800 XT 16GB GAMING OC
To overclock the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC video card we are going to use the built-in overclocking performance tuning in AMD Radeon software drivers.
When we open up the Performance Tuning and hit Custom, we find that we can control GPU, memory, fan, and Power Tuning on the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC video card. We cannot, however, raise the Voltage. We can set a maximum Power Tuning slider to a maximum of 15% over the default on the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC. We can also enable 100% fan speeds to ensure the highest overclock.
Due to the way AMD GPU frequency scaling works, which is very dynamic, we can simply raise the Max Frequency slider in increments until we find the highest overclock, or maximum allowable clock speed. We moved the slider up in 200MHz increments, all the way up to 3300MHz, with very little effect on the actual clock speed while gaming.
We settled on 3000MHz as our “highest” overclock setting, but in reality no matter what we did the actual clock speed while gaming barely moved, no matter what the slider was at. We did notice that the power draw increased, so something was happening, but apparently, the GPU is “maxed out” at its factory overclocked settings already. The power limit, even with 15%, just isn’t enough to realize any meaningful GPU frequency improvements. Still, for our overclock testing, we did leave this slider at 3000MHz as that is technically about 400MHz higher than the default setting was, so it is “overclocked.”
We were able to overclock the memory higher, however, with a noticeable increase that was measured. The default memory frequency is 19.5GHz on the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC video card, which is the reference spec. We managed to push it up to 2626MHz or 21GHz, an increase of 1.5GHz. At 22GHz, the computer locked up with a black screen, but 21GHz worked just fine. Therefore, the memory in our overclock was running at 21GHz for the overclocking results. This improved bandwidth to 672GB/s from the default of 624GB/s.
Therefore, our final overclock for the overclock data in this review is: 3000MHz/21GHz.
In the graph above, we have graphed out the default (blue line) GPU clock frequency to our overclocked (orange line) GPU frequency as reported by the single metric in GPU-Z. The factory overclock boost is set at 2565MHz on the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC, and the game clock is set to 2254MHz. According to this, we did max out at this level, but we did not sustain that potential GPU boost. The frequency hovered between 2500MHz-2540MHz primarily while gaming, at default. This is higher than the game clock of 2254MHz, which is what the game clock is set to, therefore it did come close to the boost, and higher than the game clock.
All of this is faster than the reference made-by-AMD Radeon RX 7800 XT. The made-by-AMD Radeon RX 7800 XT had an average clock speed of 2381MHz, while the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC had an average clock speed of 2530MHz. Therefore, the factory overclock on the SAPPHIRE NITRO+ RX 7800 XT 16GB Gaming OC is offering a 6% clock boost over the reference made-by-AMD Radeon RX 7800 XT out-of-the-box.
Looking at our overclocking results, we can see that what overclocking helped with the most was minimizing the minimum frequencies of the GPU clock. We are now sustaining between 2520MHz-2560MHz while gaming. It isn’t much, very small in fact, but it is a difference nonetheless. The average clock speed of the overclock is 2545MHz. This is only 15MHz higher than the default clock speed, and this shows what we are talking about. Overclocking just isn’t really eeking out much more GPU clock frequency here, the GPU is already operating at the top end of its capability out-of-the-box. There isn’t a lot of headroom left out of the Radeon RX 7800 XT GPU at this power level.
