To answer my question myself: It works partially.
1.) Samsung M393B1K70DH0-YK0
Type: DDR3 DIMM 240-Pin, reg ECC • Ranks/Banks: dual rank, x4 • Modules: 1x 8GB • JEDEC: PC3L-12800R • Voltage: 1.35V
I got 8 of these working with one CPU package on the KGPE-D16 with one of the latest Coreboot master versions:
Version: 4.5-963-gf57a768
However, the experience was not very good because I did not fit all of them at once and started with testing "partical" configurations with just two or four modules inserted. In these cases, raminit succeeded but when detecting the PCI devices the system hang up - especially when placing 4 modules in the orange slots. Also, with coreboot-4.5, I only managed to get four modules working when placing them in the slots most far away from CPU0 (two orange, two black).
Apart from that, the configured clock speed seems too low to me (the vendor bios runs the modules at 800 MHz instead of 667 MHz):
Handle 0x0007, DMI type 17, 40 bytes Memory Device Array Handle: 0x0006 Error Information Handle: Not Provided Total Width: 72 bits Data Width: 64 bits Size: 8192 MB Form Factor: DIMM Set: None Locator: NODE 0 DIMM_A1 Bank Locator: Not Specified Type: DDR3 Type Detail: Synchronous Registered (Buffered) Speed: 667 MHz Manufacturer: Samsung Serial Number: xxxxxxxxxxxxxxxxxxx Asset Tag: Not Specified Part Number: M393B1K70DH0-YK0 Rank: 2 Configured Clock Speed: 667 MHz Minimum Voltage: 1.35 V Maximum Voltage: 1.5 V Configured Voltage: 1.35 V
Cheers, Daniel