I am trying to install ubuntu next to windows. Encountering a problem with Intel RST and Ubuntu not being compatible with my NVMe SSD disk, I came across this post:
[Workaround to Install Ubuntu 20.04 with Intel RST systems](https://askubuntu.com/questions/1233623/workaround-to-install-ubuntu-20-04-with-intel-rst-systems?newreg=9be6778c7ec94bfe9e032adb9a0ae578)
The reply to that question suggests a way to fix the problem and install ubuntu without a problem. Then, there is a comment that indicates that for NVMe SSDs this fix might not work, but there are plenty of other comments that state that switching their mode to AHCI it works with their NVMe SSDs, without problems. In yet another article, however, I read that switching to AHCI might severly impair the performance of the SSDs in terms of read / write speed:

```
"Compared with AHCI, NVME protocol enables SSD to have better read-write performance, 
lower latency, higher IOPS (input/output operations per second), and lower consumption. 
An NVMe SSD’s speed reaches up to 3500MB while the speed of other SSDs is from 200MB/s to 550 MB/s."

```

200-550MB/s is still quite "fast". It might be that fast that users who switched their NVMe's to AHCI did not actually notice the degradation of R/W speed. Can anyone confirm that indeed their R/W speed dropped when switching to AHCI? If you did this to install ubuntu next to windows, did you encounter any problems related to the R/W speed? Also, as the post linked above is from two years ago, might there be a better solution for this problem as of now?

EDIT:
I have two PCs on which I'd like to install Ubuntu in parallel:

1. Dell XPS 15 9500, Bios Version: Dell, Inc. 1.12.0 08/12/2021, SMBIOS version: 3.2, with a single drive: PC SN730 NVMe SSD (1024GB)
2. MIFCOM custom-configured Desktop: Intel i9, Bios Version: American Megatrends International, LLC 5.24 28/10/2021, SMBIOS version: 3.4

So far, I only tried installing Ubuntu in parallel on the Dell XPS.

Thanks!

JZ