Hi Ragnaros,
to solve (some of) the hangs I highly recommend disabling the serial console completely as discussed here:
https://mail.coreboot.org/hyperkitty/list/coreboot@coreboot.org/thread/GA3WY...
Using 16 GB sticks did not work for me either, but I found a configuration that works if you use only some of them together with 8 GB slots resulting in at least 96 GB of fully working memory in a single-cpu configuration. This might also work with 192 GB in a dual-cpu configuration. See my posting here for details:
https://mail.coreboot.org/hyperkitty/list/coreboot@coreboot.org/message/A63P...
If you have only 16 GB sticks available, use the orange slots only or just a single DIMM in the first orange slot before going any further. It doesn't make sense to diagnose issues such a graphics output or non-booting payloads when you don't rule out inproperly working memory first.
Gfx initialization with a dedicated nvidia GPU and booting from NVMe works fine for me, although I'm not using 4.11 but an older version (master somewhere between 4.8 and 4.9). I just use a text-based ("legacy") graphics without splash and boot the kernel from there which then initializes the graphics properly and switches them to graphics mode. No issues with this so far.
Regarding the fans: If you run linux, you can control them in userland using a tool such as "fancontrol" if you don't want to control them by the BMC or don't have it installed. The fancontrole profile I created for this (attached) results in the following RPM and temperature levels at the moment in my (computer) case:
GPU core: +0.90 V (min = +0.90 V, max = +0.90 V) temp1: +60.0°C (high = +95.0°C, hyst = +3.0°C) (crit = +105.0°C, hyst = +5.0°C) (emerg = +135.0°C, hyst = +5.0°C)
fam15h_power-pci-00c4 Adapter: PCI adapter power1: 51.28 W (crit = 114.49 W)
...
fan1: 596 RPM (min = 329 RPM) fan2: 584 RPM (min = 329 RPM) fan3: 0 RPM (min = 329 RPM) ALARM fan4: 0 RPM (min = 329 RPM) ALARM fan5: 585 RPM (min = 329 RPM) fan6: 696 RPM (min = 329 RPM) fan7: 0 RPM (min = 329 RPM) ALARM fan8: 0 RPM (min = 329 RPM) ALARM temp1: +68.2°C (high = +70.0°C, hyst = +65.0°C) (crit = +85.0°C, hyst = +80.0°C) sensor = thermal diode temp7: +25.8°C (high = +70.0°C, hyst = +65.0°C) (crit = +85.0°C, hyst = +80.0°C) sensor = AMD AMDSI temp8: +0.0°C (high = +70.0°C, hyst = +65.0°C) (crit = +85.0°C, hyst = +80.0°C) sensor = AMD AMDSI
...
k10temp-pci-00cb Adapter: PCI adapter temp1: +22.9°C (high = +70.0°C)
Normally, my fans run at around 350-400 RPM in idle and are hardly hearable. The increased rotation levels are probably due to the fact that I didn't clean the dust filters for a while. If you use the profile you might need to adjust the devpath probably, but you can try to create your own with pwmconfig and then tweak the values.
Cheers, Daniel