XPS 9360 and Samsung PM961 SSD

Are you running McAfee?  If so, you might try shutting it down while testing.

Most of the Samsung drives have been getting a firmware upgrade.  I did see one thread which suggested not yet doing that upgrade, but you might check to see if there is one.

There is a fairly long thread/sticky which discussed these things.  It may still be in the General section of the forum.  Maybe a search for NVMe would show it.

As an additional note, you really shouldn't tinker with the write cache buffer flushing setting.  I would strongly recommend changing that back, especially since that isn't going to be your bottleneck on this particular system.  That significantly increases your risk of data corruption.  I realize that laptops have batteries and are therefore less likely to suffer power failures, but an unexpected hard shutdown due to a thermal issue or something could still trigger it.

The XPS 13 models at least up to the 9360 runs the 4 PCIe lanes feeding its NVMe slot in power-saving GT2 mode, not max performance GT4 mode.  This is roughly equivalent to running only 2 PCIe lanes in max performance mode.  This has come up a few times in other threads already, and nobody from Dell has explained why it's done this way, but there's no setting to change; that's just how the system is.  The XPS 15 runs in GT4 mode, and judging by early storage benchmarks, the XPS 13 9370 also appears to run in GT4 mode, but obviously that doesn't change anything for the 9360.

@jphughan @Saltgrass thanks for your answers

Regarding write-cache buffer flushing, since it does no good I already reversed the change. 

About the 9360 2 lanes / 4 lanes PCIe, I thought it only apply to the usb-c port. And since the "Current Link speed" in hwinfo result shows the maximum speed, I thought it can utilize the drive at full speed. Nevertheless, I will make further study on the GT2 / GT4 mode and if there's nothing can be done about it, I will accept the reality and say goodbye to the 3secs boot time.

Thank you for your info.

After reading some other threads, I can see that I am not the only one with this issue. Althought I haven't found any proof that indicates Dell actually configured CPU bus speed to 2GT/s OPI, I will trust other comments and accept the situation. (But still, a confirmation from a Dell engineer would ease my mind even better)

I have always been a little confused by the comments in the Quote from the Samsung driver install instructions.  It shows the Dell system is a PCH M.2 drive which is different from having direct PCIe lanes.

Even though I may not understand the situation, I could swear my 9365 was, at one time, getting the advertised speeds for my Samsung 960 Pro M.2 drive.  I will continue to try to find that picture but now I am only getting the 1800 number using the Magician benchmarking.  It is possible, some Bios upgrade has changed the original configuration I had back in February.  There has been a Samsung Firmware upgrade but not sure why Samsung would dumb down their drive performance.

System Configuration

Windows Operating System shall successfully load the driver only when Samsung NVMe SSD 960 PRO, 960 EVO or 950 PRO is installed to

 PCIe slot directly connected to CPU or

 M.2 or PCIe slot connected to PCH.

However, in the PCH case, Windows Operating System cannot load the driver under following BIOS configurations where

 PCH Storage Configuration is set to "Raid Mode, or

 NAND/Storage Remapping option*" is enabled.

* The option name can be different according to M/B manufacturers.

Please refer to your M/B manual.

Hi,
I have the same problem on my xps 9360 with Samsung 970Evo, no more than 1800 GB/s instead 3000 GB/s. Have someone find a solution how to increase ssd speed to specified 3000 GB/s?