Thank you for your explanations.
In terms of performance throttling, stability and endurance, it seems the GIGABYTE B650M AORUS ELITE AX offers the lowest temperatures for the 7950X at 56c, which is cooler than virtually all of the X670E boards shown in Hardware Unboxed's X670E's videos?
B650 temps
View: https://youtu.be/ZtHOOyWYiic?t=1311
X670E temps
View: https://youtu.be/ibNjPksgaOA?t=266
Remember that, just as Steve said,
any of the boards that passed the test are more than fine for any situation. He failed to overheat them running Cinebench multi-core on that R9-7950X CPU. That's the absolute worst-case scenario and all of those boards passed with flying colours. The few degrees difference between them means nothing because all of those temperatures were well within spec.
The ASRock X670E PG Lightning is US$50 more expensive where I am. I'm not sure if it's worth more if the performance benefits arent justified?
Well, without knowing where you are, it's hard to make an accurate assessment so I just wanted to bring the X670E PG Lightning to your attention. It easily passed his VRM thermal test and because it has an X670E chipset, it has extra features that a B650 board doesn't. Remember that there are actually five tiers of AM5 chipsets; X670E, X670, B650E, B650 and A620.
Puget systems has an article describing the differences between the B650, B650E, X670 and X670E chipsets. Take a look and see what you think. Ultimately it's up to you but I don't believe that you should be paying close to $200 for a B650 board (and especially not a a µATX model). Out of those three, I would definitely choose the ASRock B650 Pro RS because it's priced
right for a B650 motherboard and it's a full-sized ATX. Remember that those extra fifty dollars will give you 16 PCIe5 lanes, something that means nothing today but might mean the difference between upgrading and not needing to down the road. After all, if AM4 is any indicator, AM5 won't be irrelevant anytime soon.
Here's a link to the article from Puget Systems: