Dark days appear to be ahead for those of us who think they can get away with powering the next generation of flagship graphics cards with passive PSUs. Igor Wallosek has shared his projections on how power hungry the GeForce RTX 4090 should be, and they indicate that the its Lovelace-based GPU alone might consume a relatively insane 450 watts. This is equivalent to the graphics card power that NVIDIA listed for its recently launched GeForce RTX 3090 Ti, a figure that’s already 100 watts higher than its standard counterpart. Wallosek’s calculations also imply that the GeForce RTX 40 Series will, as rumors have suggested, include models with TGPs of up to 600 watts.
Where the 600 watts of the NVIDIA GeForce “RTX 4090” come from – a calculation of GPU and components | EXCLUSIVE (Igor’s Lab)
This time, the large Ada card’s board power TGB (whether it will be called RTX 4090 or not) is 600 watts, which should be considered as set. Again this time we want to calculate down how much could then still left for the chip itself. And this is where it gets interesting, because you can extrapolate voltage transformer losses, extra-low voltages and other losses quite well based on the last generations. Well, I explicitly asked about the memory, because I’m not a psychic. With 3.4 watts per module (according to my information), Micron is within the bounds of what could be expected anyway due to the increased clock. The storage expansion itself is rather secondary. That makes a total of only about 40 to 41 watts for 24 GB (12 modules), instead of the 60 watts on the GeForce RTX 3090.
The four voltage converters of the memory should have an efficiency of about 60 to 70% in this simple design, I plan here together with the components involved about 15 watts of losses for the whole circuit including the MOSFETs, coils and caps. This is not little, but also not unusual. For the low voltages with the usual 1.2 volts, 1.8 volts, 5 volts and the other things like the MCU, the shunts, the filtering of the rails, etc., I put about 10 watts, for the fans an average of 5 watts, although it was also rumored here that they would not be directly included in the limit.
If you extrapolate the power consumption and look at the traces, you can almost assume a doubling of the board losses, since more phases also mean more conductor traces. The GPU voltage converters (NVVDD), if they are very similar to those of the 3090 Ti, should show an efficiency of about 90%, which would bring us to about 50 watts. This is also about double what the RTX 3090 converted into heat, and it would then leave about 450 watts for the GPU. In relation to this, the AD102 would only consume slightly less than twice the electrical power.