I got an upgrade recently (NVMes), in short : upgraded my OS drive + Gaming drive both in NVMe PCIe Gen3 and both in the M2_1 and M2_2 slots. Everything is good in the BIOS / x4 mode activated / nothing plugged into SATA5 and SATA6. The thing is its a LOT slower than my old Samsung SSDs now, took 20-30 seconds to get into Windows (with NVMes) instead of 5s before (with SSDs). Tested RAM in Manual/XMP1/XMP2 Tried Fast Boot ON and OFF CSM ON and OFF Secure Boot ON and OFF Latest mobo BIOS (1903) and VBIOS, also tried earlier ones. I noticed on the MB that everything is much slower to initialize, especially the RAM and the VGA. I'm really confused since the NVMes are much faster than the SSDs (and working well under Windows, with the right speeds). I tried everything, did a trace of my boot with Windows Performance Recorder and cannot find why.
CPU Intel Core i7 9700K @ 3.60GHz 42 °C Coffee Lake 14nm Technology RAM 16,0GB Dual-Channel Unknown @ 1600MHz (16-18-18-36) Motherboard ASUSTeK COMPUTER INC. ROG MAXIMUS XI FORMULA (LGA1151) 29 °C Graphics LC32G7xT (2560x1440@240Hz) 2047MB NVIDIA GeForce RTX 3080 (MSI) 38 °C Storage 465GB Samsung SSD 840 EVO 500GB (SATA (SSD)) 34 °C 931GB Samsung SSD 850 EVO 1TB (SATA (SSD)) 39 °C 931GB Western Digital WDS100T3X0C-00SJG0 (Unknown (SSD)) 232GB Western Digital WDS250G3X0C-00SJG0 (Unknown (SSD))