AMD GPUs have never been known for their overclocking prowess. The same goes for Nvidia's GPUs, to be fair to AMD. These days, GPUs will boost as high as they can all on their own; going beyond that usually requires more voltage. However, that's generally not possible, as both companies lock that down to prevent cards from being damaged. Noted German overclocker de8auer sidestepped that pesky limitation recently on a PowerColor Liquid Devil Radeon RX 7900 XTX by using a voltage modding kit, and he achieved some impressive results. Overall, he got the card up to around 3.4GHz, allowing him to achieve a score in Time Spy Extreme that was nipping at the heels of the RTX 4090.
First, it must be noted that the card he used for testing is a premium version of the RX 7900 XTX sold by PowerColor. It's similar to the now-shuttered Kingpin series from EVGA, built for overclocking and sold at a premium. This GPU is already factory overclocked and has a high-end EK liquid cooling water block attached. The block covers the entire PCB, too, so it cools the GPU, memory, and VRM. As Wccftech notes, it's currently selling for $1,819 on Newegg, so this is an ultra-premium GPU.
The key to enabling such a high overclock was the premium liquid cooler and an ElmorLabs EVC2SE kit allowing manual control over the card's voltage. The Liquid Devil is also already overclocked relatively high compared to factory clocks. It's got a 2510MHz game clock and a 2860MHz boost clock, which are 240Mhz and 180MHz higher than stock.
Like any good overclocker, de8auer started slowly and began upping the voltage in small increments. At 1.045V, the card was consuming 500W and running at about 3GHz. In the final run, he got the card up to 3.4GHz at 650W of power consumption. The liquid cooling did an impressive job, keeping the GPU at just 47C. The card's hotspot was at 88C, though, so it didn't have a lot of headroom beyond those clocks. De8auer states that the cooling was becoming increasingly inefficient at that clock speed, though, so going further wouldn't have made much sense.
His efforts were enough to get him into the upper echelons of the Time Spy Extreme Hall of Fame. However, in a nod to how fast things can change in the overclocking world, he states his score was enough to get him ranked 9th overall. Checking the listing now, though, he's already down to 15th. Looks like it's time for an LN2 run on that GPU.