When many people upgrade their computers, the first thing they want to change is usually the graphics card. After all, the FPS when playing games is too low and the image quality cannot be increased. The most intuitive thing is that the GPU is not powerful enough. However, if the CPU is too old, even if you replace it with a high-end graphics card, there may be a situation where the card performance is obviously sufficient, but the performance is not enough. This is the so-called CPU bottleneck.
According to foreign media Tom’s Hardware According to reports, the foreign YouTube channel TrashBench recently conducted an experiment. It used the Intel Core i7-6700K processor launched 10 years ago and paired it with the RTX 3080. After that, it was found that the GPU usage was low. It tried to solve the CPU bottleneck problem through extreme overclocking. It even tried to pull the voltage to 1.7V to challenge 5.2GHz and 5.3GHz. Although in the end, it was still unable to get the RTX 3080 usage to reach 100%, but at least from about 60% to 74%.
Image source: TrashBench
In order not to let the CPU drag down the RTX 3080, a foreign YouTuber pushed the i7-6700K from 10 years ago to 1.7V to challenge the extreme overclocking
Core i7-6700K is a processor launched in 2015 and one of the representative models of the Skylake architecture. According to Intel’s official specifications, the i7-6700K uses a 14nm process, 4 cores and 8 threads, a base clock of 4.0GHz, a maximum Turbo of 4.2GHz, and a TDP of 91W. By 2015 standards, this is a high-end gaming processor. But in 2026, 4-core and 8-thread specifications paired with high-end graphics cards will obviously not be enough to play modern games.
This time TrashBench overclocked the i7-6700K all the way to the limit. He tested three main settings: 4.7GHz with 1.4V, 5.0GHz with 1.56V, 5.1GHz with 1.6V, and 4.7GHz was still done with air cooling:
Image source: TrashBench
When it comes to 5.0GHz and 5.1GHz, we switch to homemade water cooling and put the water cooling system into an ice bath to check the temperature:
Image source: TrashBench
He then tried to use 1.7V to push to 5.3GHz, but this setting failed to stabilize. I would also like to remind you that 1.6V to 1.7V is already a very aggressive voltage for the daily use of ordinary players. It is not only a problem of temperature and power consumption, but also a great risk to the life of the CPU. This is more of an experimental challenge, and I’m not suggesting that you follow the same steps on your own old platform:
Image source: TrashBench
Below is the configuration that he tested and found to run stably after overclocking:
Image source: TrashBench
Next, let’s look at the actual game test.
In the “Cyberpunk 2077” test, the i7-6700K was 91 FPS at the original factory settings, and increased to 104 FPS after air cooling and overclocking, an increase of about 14%. After overclocking with ice bath water cooling, it reached 109 FPS, an increase of about 20%. “Shadow of the Tomb Raider”, “Assassin’s Mission 3” and “Far Cry 6” only improved by about 7% at the 4.7GHz air-cooling setting, and the gap is not huge. After overclocking with 5.0GHz ice bath water cooling, the average improvement came to 11.3%:
Image source: TrashBench
The improvement of 3DMark Time Spy is obvious. 4.7GHz is 19% higher than the original one, and 5.0GHz is 24% higher. It is not difficult to understand that the benchmark software is more sensitive to CPU clock changes, so the numbers will look better.
It is worth noting the RTX 3080 usage rate. As you can see from the figure below, the Core i7-6700K usage rate is 64% at the original factory settings, and increases to 70% after air cooling and overclocking:
Image source: TrashBench
The same goes for Shadow of the Tomb Raider, up from 61% to 68%:
Image source: TrashBench
Comparison of RTX 3080 usage among three configurations: 17% vs 30% vs 29%. It can be seen that air cooling and overclocking alone can actually effectively increase the usage of RTX 3080 graphics card:
Image source: TrashBench
Although ice bath water cooling + higher clocks result in higher FPS, the graphics card usage does not increase significantly. This also means that increasing the clock does help, but when the core number, architecture and memory environment of the platform itself cannot keep up, simply pulling the clock cannot completely eliminate the bottleneck.
Full video:
Source: KOCPC Chinese