Power Spikes - Furmark

I thought it would be interesting to see how the power spikes are affected with the 600 W 12VHPWR connector using Furmark, also known as a power virus. With the Powenetics system, I am able to catch every power spike and not have the EMI problems that current clamps have. More importantly, I can have both voltage and current readings at the same time, so it is easy to get accurate watt readings.



The difference in power spikes is impressive between the 450 W and 600 W 12VHPWR connectors, and the slight performance difference doesn't justify it. The Palit Gamerock RTX 4090 doesn't have the best VRMs though, and the power spikes once you utilize the 500 W power limit clearly indicate this. Other RTX 4090 implementations with better VRMs might not have such high power spikes, but if you push them to the 600 W power limit, which some of them support, you might have even higher power spikes. The NVIDIA RTX 4090 FE, the Asus RTX 4090 Strix OC, and the Gigabyte RTX 4090 Gaming OC all have 600 W power limits, but I don't have any of them for evaluation.

Let's take a look now at some detailed power analysis graphs.

Furmark Stock Clocks- 12VHPWR 450 W

Furmark Overclocked - 12VHPWR 450 W

Furmark Stock Clocks - 12VHPWR 600 W

Furmark Overclocked - 12VHPWR 600 W

Furmark Operating Temperatures

The power consumption in Furmark is higher with the 600 W cable, so it is natural to record higher operating temperatures.

Conclusion

The performance difference between a 450 W and a 600 W 12VHPWR connector is zero for the Palit Gamerock OC RTX 4090 with the power limit set at 500 W, under stock speeds. There was an improvement in operating temperatures, even with slightly lower fan speeds. There is a slight difference between the 450 W and 600 W connectors at overclocked speeds, but with this specific RTX 4090 implementation, the increase in power spikes means that the VRMs are pushed hard. Given that the average gaming power consumption of an RTX 4090 is around 350 W, it doesn't make much difference whether you use a 450 W or a 600 W 12VHPWR connector. If you plan to overclock the card hard, notably decreasing its efficiency, using a 600 W 12VHPWR connector will make a difference since it will allow the card to draw more juice.

The lower temperatures under stock and OC speeds with the 600 W 12VHPWR connector, compared to the 450 W one, are most likely to do with the card's VRMs, which operate better with the full capacity of the 12VHPWR connector. It seems that the 450 W limiter, when Sense0 and Sense1 on the 12VHWR connector are set to open and ground, affects the VRM's operation, increasing ripple as the limiter is engaged, leading to higher GPU temperatures. This is the only explanation I can provide. Feel free to leave a comment if you have to suggest something different.

The results of today's article lead to the conclusion that an ATX v3.0 ready PSU with a native 12VHPWR connector, is not required to operate an RTX 4090 properly. Even with the Powenetics system, with more than 1000 Hz polling rates or less than 1 ms between power measurements, I couldn't "catch" a power spike exceeding 700 W, while the PCIe 5.0 standard speaks for up to 1800 W power spikes. I cannot know what the upcoming GPU generations will bring. Still, you can safely use proper adapters and your existing PSUs for the moment, as long as they have enough max power to support the Ada Lovelace GPU's energy requirements.