How would you know without actual reviews ? Intel has been failing hard with their choice of thermal paste over solder.
This part made sense to me, until I saw that Knights Landing Xeon Phi chips have paste under IHS as well. It can't be merely for saving a few cents.
Anyone remember the article about how small dies are more fragile when using solder? And why smaller die chips went for paste?
Let's expand that a bit further. The reason you can significantly undervolt GPUs and overclock GPUs is because out of the factory, its set to a spec that would result in low as possible RMA returns. And since factories create millions of these chips, you have to set it to the lowest common denominator, that is, the crappiest chip. While having numerous bins like Intel does might mitigate that somewhat, there's a limit.
So if soldering was done on a small scale, it would make sense, because more attention could be given. But with millions sold, you can't really fine tune it.
But if that's true why would the older chips all use solder under IHS?
Maybe its related to the fact that CPUs run closer to their mechanical and electrical limits than before, made worse by the fact that Moore's Law scaling is dying. Things like Turbo mode and AVFS is designed to push the silicon close to the limits as possible.
Paste, would not only preserve long-term reliability, but reduce TTM by reducing amount of validation needed because you no longer need to run as stringent mechanical reliability tests.