1. The temps were not far off with the stock fans on the GPU, however in order to maintain the temps at acceptable levels the fan speed had to be quite high and therefore the noise was not acceptable (unless you wear headphones i guess), especially since the PC is in the living room and will be acting as HTPC too.
2. did not even try since I had read extensively other users with the same or very similar configuration that intake was worse than exhaust.
3. Indeed as I said earlier, regular temps (updated info after having the system up and running now almost a month) are as follows:
browsing-idle-general use: CPU 40-45C and GPU 39-43C
gaming: CPU up to 70C and GPU 79C
benchmarking max temps (both CPU and GPU benching): CPU 80C and GPU 81C. But this is an extreme scenario and these temps will never be seen unless benching.
As I said, even in most demanding games and settings, both CPU and GPU remain below 70C and most importantly the whole PC is inaudible
of course it took a while to get the fan profiles right in the Asus Fan Expert; especially the spin up and spin down times so that they remain silent.
As a side note, I was initially really concerned when I first setup the rig, cause I was seeing the NVMe temps above 60C with no particular high load, and would usually hover around 62C. But ever since I did the mod on the GPU shroud and fans and also added the 3rd fan on the CPU cooler, the temps on the NVMe also droped. Now it sits at 49-50C on usual desktop use and gets up to 60-62C if I purposely push it with read-writes.
Last but not least, I believe (have no hard data for this, only what I have observed) there is an element of temp saturation in the whole system and the temps. What I mean is that the case itself (along with all other parts of the system) the longer they run and being pushed, the more heat is radiated and there is a point (after hours of course) that the case itself, especially on the rear and lower part of it, is quite hot. In return this means that if for example I am gaming for a few hours, the temps will rise about 1-2C more but the case itself (being metal) absorbs and radiates) a lot of heat too).
Hope my English was good enough to describe what I wanted
@tinyitx let me know if I can help you in any way or if you need more info