Yep but took some dialing in. I've already been using MSI AB, and the NVIDIA app (in case AB gets ignored) to limit power to 70% but I've got a custom power curve in AB to undervolt as well. Using optiscaler I limited FPS to 70, sometimes 75, since I mostly play RPGs and are more interested in IQ than frames. I also, depending on the game used MFG x3 with a DLSS override to use the NVGX render, just to ensure the most recent dll was being used in case a game had an older one. Then I normally had the DLSS 5 slider set to between 70 - 100% depending on the game. DLSS was set to between Performance (transformer v2) and Quality (transformer v1)
All of this resulted in keeping my 5090s (one w/ 5800X3D and other 9800X3D) at between 250W - 400W! Mileage can vary greatly with the game, and I don't have screenshots since I was testing about a dozen games but I was most impressed with Blood of Dawnwalker but had to disable MFG due to horrible flickering. However, with DLSS 5 at 70%, and the above settings, it looked fantastic and hung between 60-75 FPS using DLSS quality.
When possible it will opt for OptiScaler, which up until now I knew about but hadn't used, and now I'm a huge fan of. Older games will need other paths and I had mixed experiences with those and need to do more testing with. Powerdraw for them is often minimal compared to newer titles.
For those used to digging into toggling PC/GPU settings, this is a godsend but it can be a siginifacnt learning curve for those who are not. Best part, if you really don't like it, only one click to restore/remove but I can't emphasize enough, given the risks of power hungry 5090s, is to tame it before trying. The power draw I got it down to matches what I'd been seeing before trying this but with the added IQ, so I'm very happy. I also updated to the latest NV driver from last week and it seemed to be bug free but I also always recommend doing a restart since they can break the hooks for AB, even if you restart the app. I saw some strange behavior during testing when I didn't and stuck to this approach once I moved on to installing on my 9800X3D rig.
Last note, moving the slider to 70% often allowed higher FPS, upwards and over 115 FPS, but limiting frames to 70-75 really was the icing on the cake for perf/power draw. At 115 FPS power usually hung 350-400 due to the limits via AB. All this, using max/ultra settings including RT at 4K.