G5 5090, Samsung PM991a NVMe slow write speeds

Always include exact PC model in your posts.

Samsung drivers don't work very well when BIOS is set to RAID. If you changed BIOS to AHCI, without setting Windows to install AHCI drivers, I'm surprised Windows will still boot.

Depending on the exact PC model, the NVME slot may only be x4 so it's not going to be as fast as the same SSD installed in a faster NVME slot when they wrote the speed specs....

At least for some users with XPS 8940 PCs and a similar issue, they did the following:

1. Update BIOS to the latest version for your PC model. If this were my PC, I'd update BIOS manually from a USB stick, not via SupportAssist or even inside Windows.
   
   
2. When that's done, boot PC and tap F2 to open BIOS setup. Look for a "BIOS default settings" option (not a “factory settings” option) and select the right option. Confirm the reset, save the change and exit setup.
   
   
3. Test SSD again

Sorry for not posting the model. It is the Dell G5 5090 with 10700F.  

I have updated BIOS, but from within Windows.  I can try and reflash with a USB via BIOS.  I'll try the steps you've provided and report back. 

Thank you

@japaul32  - If you already updated BIOS to the latest version successfully in Win 10, don't do it again.

I suggested updating BIOS outside Win 10 because that usually has fewer risks of failure which can brick the motherboard, than doing it inside Win 10.

So just try resetting BIOS to the default settings....

Will do.  I'll reset the values to default in BIOS and report back. 

I reset BIOS to default settings. Unfortunately, that did not make a difference.  Write speed is 133 MB/s. 

Did you install the Samsung driver?

What version of BIOS is installed? BIOS v1.4.0 is the latest.

Is BIOS set to RAID or AHCI now? If it's RAID, you should change it to AHCI, the right way:

1. Open Cmd prompt window, run as administrator
   
   
2. Copy-paste this command, which will start Windows in Safe Mode the next time you reboot:
   bcdedit /set {current} safeboot minimal and press Enter
   
   
3. Restart the computer and enter BIOS setup
   
   
4. Change the SATA operation mode from RAID to AHCI
   
   
5. Save the change and exit Setup and Windows will automatically boot to Safe Mode
   
   
6. Open Cmd again, as in step #1
   
   
7. Copy-paste this command, which will start Windows in Normal Mode the next time you reboot:
   bcdedit /deletevalue {current} safeboot and press Enter
   
   
8. Reboot and Windows will automatically start with AHCI drivers enabled

According to Dell the most current BIOS for my system is 1.1.2.  Also, my system is a G5 5000 (my bad). I haven't been able to find a new driver version for this drive.  

I set ACHI using the method you provided previously.  It didn't do much to the write speeds. 

I tried to install this firmware, but it does not work with this drive.  I think I'm just at a point where I'm better off buying a new NVMe.  I've reached to Samsung regarding drivers and firmware as well. 

The install log doesn't offer any info as to why it fails. 

@japaul32  -  Always helps when you give us the right model number.... 

Dell offers a firmware update  for the Samsung PM991 NVME SSD installed in the G5 5000 that: "Improved the performance of the solid-state drive (SSD)".

CAVEAT: That page says "PM991", not "PM991a". I don't know what the difference is between those two, so it might not install if it's not suitable for the "a" version.

Maybe that will help...

Were you logged into an account with administrator privileges?

It's possible that firmware version is already installed or maybe Samsung fixed something else in the hardware so that update isn't necessary for the "a" version.

Who's to say a new NVME SSD will be any faster? And even if it is, will you actually notice it in the real world, eg when you're not just running benchmarks?

Yes, I was. It looks like the firmware on the PM991a is newer. 

You're right, there's no guarantee.  My system is slow when using productivity and construction apps (AutoCAD, Blue Beam).  More so than my previous system, which was an ancient PC with a 4790k.  

How much RAM in this system?

Are all your other G5 5000 drivers up-to-date?

The system shipped with 16GB in l of ram dual channel.  All of the the other drivers are update, and I've updated windows recently as well. 

It looks like at least one other person has the same issue. 

https://www.dell.com/community/Inspiron/New-Dell-Inspiron-5000-with-really-slow-samsung-PM991-256GB-nvme/m-p/7882567/highlight/true#M118779

And BIOS is still set to AHCI?