They detect that the Intel Core i5 9400F processor has two different versions and neither has TIM solder, they only carry bad Intel thermal paste.
We still don't quite understand Intel Core 'F' Series processors, as do many users. These processors have a disabled iGPU and all other features are the same as their counterparts without the 'F'. Also, the price of the processors without iGPU, are equal to those with the iGPU enabled. These processors also return to the much maligned thermal compound, therefore they do not have the DIE and IHS soldered.
Intel does not solder the DIE and IHS of the Core 'F'
The positive thing about the Coffee Lake Refresh processors is that the IHS and DIE were re-soldered. This was very celebrated because it allows to improve the cooling of these processors. But they have investigated what the Core i5 9400F are like, opening the processor and discovering that these new processors go without TIM solder.
In addition, a recent firmware update for MIS motherboards confirms compatibility with two Core i5 9400Fs. As found, the P0 model is based on eight TIM welded cores and would have two cores disabled. The U0 model would be purely six-core and uses Intel's low-grade thermal compound. It also stands out from the U0 model, that the PCB used is much thinner and the IHS design is also simpler.
Implementing TIM welding offers us better heat transfer between the DIE and the IHS, which allows the processor to work at a lower temperature and lengthens the durability. This is also good for overclocking, which offers more capacity.
We do not know if this strategy is exclusive to this processor or it will also reach other processors in the family such as the Core i9 9900KF. We don't know much more at the moment, but the look of these processors is pretty bad.
Source: TH
