https://www.techpowerup.com/299175/nvidia-rtx-4090-boosts-up-to-2-8-ghz-at-stock-playing-cyberpunk-2077-temperatures-around-55c
 
NVIDIA GeForce RTX 4090 is turning out to be a cool operator, with the GPU reportedly boosting up to 2.8 GHz (2810 to 2850 MHz) at stock settings, when playing Cyberpunk 2077 at 1440p, in its "psycho" settings preset. with DLSS and Reflex disabled. At native resolution, the RTX 4090 scores 59 FPS (49 FPS at 1% lows), with a frame-time of 72 to 75 ms. With 100% GPU utilization, the card barely breaks a sweat, with GPU temperatures reported in the region of 50 to 55 °C. With DLSS 3 enabled, the game nearly doubles in frame-rate, to 119 FPS (1% lows), and an average latency of 53 ms. This is a net 2X gain in frame-rate with latency reduced by a third. The power-draw is also said to be significantly reduced. The card pulls up to 461 W when rendering at native-resolution, but this drops down to 348 W with DLSS 3 "quality," a 25% reduction.
 
As large as the heatsink is I would assume the temps would be good. 

What version of GPU boost is the 4090 using? I would assume 3.0, but have not seen it mentioned by NVidia like they normally show off.

The one thing I personally don't like is we keep hearing "DLSS 3" which is a feature only on this series so far and the entry gate to have DLSS 3 would be $999 at least right now. To me it's about the game list to make DLSS 3.0 really a thing that developers are supporting. At this point AMD FidelityFX is open source so it works on NVIDIA cards and also PS5 and Xbox Series X so of course games are going to support that since it will make the games run better on consoles. On the other hand DLSS 3.0 has no development benefit to console and probably well under 1% of PC gamers will be able to use the feature. Right now the 3080, 3080Ti and 3090 make up about 1.5% of gamers in the Steam survey combined and that 3080 isn't a $999 card or at least the MSRP wasn't.
 
I should say that this could change at any time and NVIDIA could release a 4060 for $350 that could support DLSS 3.0 but for right now if prices of cards remain high I am not sure it's a feature that will get a lot of support after launch when they display it as a major feature with a lot of tests. I really want to point that out since when the NDA lifts and reviews can be published it will be interesting to see if reviewers focus on games that now have DLSS 3.0 modes and are required to benchmark that mode enabled vs. off. I personally am not sure it's a feature to count on support.
 
The other thing that could impact this thought is if DLSS 3.0 has a feature to work with older generations in a DLSS 2.0 method. If that was to be the case that it's just new features that would require the new hardware to get the most out of DLSS being enabled then I could see it being good to support since the 3060 even supports DLSS.